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The comparative inaccessibility of the Parva naiuralia 
(they exist in English only in Taylor s paraphrase) has 
induced me to prepare an English version of these im- 
portant tractates. To this I have added a translation of 
the De anima, in order that English readers might have in 
a single volume a practically complete account of Aris- 
totle's psychological theories. Such a work seemed to me 
to be all the more necessary at the present time in view 
of the need of available primary sources for historical 
research in philosophy and psychology. An adequate 
history of psychology has not as yet been written. 

The translation of Aristotle's works, owing to their 
crabbed Greek, their puzzling lacunae and breviloquence, — 
oftentimes they are almost unintelligible jottings intended, 
perhaps, for lecture-notes or for later elaboration which 
they never received, — has at no time been regarded by 
scholars as an easy or attractive task. It is only their 
immense historical significance and the intrinsic value of 
their content that could induce one now-a-days to set 
hand to the work. The De anima and Pa/rva naturalia 

cannot be said to be in a more satisfactory condition 



than the other writings of Aristotle. I have, however, 
attempted no speculative reconstruction, such as has been 
applied with some success to the Politics by Barth^emy- 
St.-Hilaire and Susemihl. The attempt has not been very 
fortunate in the case of Elssen's restoration of the De 
cmi/ma, and, so far as I know, his predecessors in the 
same endeavour have not been more successful. Qrowing 
distrust of the radical treatment of texts seems to me a 
hopeful mark of critical scholarship. My translation is 
based on the text of the late Wilhelm Biehl (Teubner 
series), whose emendations I have constantly compared 
with the Berlin edition, and with whose conservative 
judgment I have generally found myself in accord. Where 
I have deviated from his text, I have stated my recMiing 
in a foot-note. In 1897 I made a careful examination of 
Codex E (Parisiensis Regius 1853), the best of the MSS. 
for the texts here translated, but as Biehl collated this 
Codex in the same year and published his Parva Tiatur- 
alia the year following, my work was rendered unneces- 
sary. In any case, I was not interested primarily in 
textual questions, excepting in so far as the establishment 
of the text was ancillary to the establishment of doctrine. 
I have aimed, therefore, to avoid the accumulation of notes 
of a purely scholastic kind, which in the present volume 
could only be marks of a diligent pedantry, and while I 
have neglected no source of information and assistance 
amongst ancient or modem commentators, I have rigidly 
excluded all such matter as had no real interest for the 
doctrinal exposition of the treatises in hand, or for the 
history of science. 


M. Rodier's text of the De anima with translation and 
notes (2 vola, Paris, 1900) is a notable product of French 
scholarship, in which the widely scattered materials of 
interpretation have been brought together and utilized with 
singular industry and insight. M. Bodier's volumes have 
been prepared with a bias of interest different from that 
with which my own work is written, concerned, as they 
are, largely with questions of text, of philological criticism, 
and of the literary aspects of interpretation. They do 
not include the Parva naturalia. The aim of the present 
translation and introduction is rather to make easily acces- 
sible to English scholars the scientific content of these 
Aristotelian treatises, and thereby to facilitate inquiry into 
the history of philosophical and psychological ideas. For 
this reason my work does not duplicate the much wider 
and more ambitious investigations of M. Rodier, to whose 
scholarly labour I wish to pay my warmest tribute. 

I desire further to record here my grateful acknowledg- 
ment of various and valuable help from my colleagues, 
Professors Bennett, Creighton, and Titchener. Professor 
Titchener has read the proof-sheets of the entire volume, 
and to him I am especially indebted for many suggestions 
and criticisms. 

Cornell Universitt, Ithaca, N.Y., 
July 29th, 1902. 




I. Thb Soul and Lifb xv 

IL Thb Faculties of the Soul xxvi 

IIL Nutrition and Reproduction xxix 

IV. Sensation xxxvX 

y. The Common or Central Sense \^ 

VI. Imagination and Memory Ivi 

VII. Practical Reason and Will Ixiv 

VIIL Creative Reason Ixxi 


Book I. History of Psychological Theories — 

Chap. L Methods of investigation, separability of the soul, 

relation of soul to body 1 

ii History of theories, theory of Empedocles, theory 

of Democritus, theory of Anaxagoras - - 10 

iii. The soul and motion, pre- Aristotelian theories - 18 

iv. The soul a harmony, the soul and the body, the 

monadic theory - 26 

V. The soul and the elements, the soul and its parts, 

divisibility of the soul - - - ' - - 32 

Book II. Faculties of the Soul — 

Chap. i. The notion of substance, definition of the soul - 42 

ii Animate and inanimate, the principle of life, the 

soul and body - - 48 

iii. Various meanings of soul 54 





Chap. iv. Soul and final cause, the soul and nutrition, 

principle of nutrition 67 

V. Potential and actual, sensation and thought - - 64 

vi Sense-qualities 69 

vii. Vision and its medium 71 

viiL Sound and its medium, definition of voice, vocal 

utterance 75 

iz. The sense of smell 82 

X. The sense of taste 85 

XL The sense of touch, the medium of touch - - 88 

xii. Relation of sense-organ to stimulus, media of 

sensation 93 

Book III. Sensation, Imagination, and Thought — 

Chap. i. The ' common sensibles ' 95 

ii. Sense-perception, the ' common sense ' - - - 99 

iii. Imagination, imagination and truth, imagination 

and light 105 

iv. Theory of reason, abstract thought - - 112 

V. Active and passive reason 117 

vi. Thought and truth 119 

viL Thought and images, thought and its object - - 122 

viii. Ideas and images 126 

V ix. Powers of the soul, reason and desire - - - 128 

* X. Psychology and conduct, function of deeire - - 132 

. xi. The moving principle 136 

xii. Nutrition and sensation, sensation and well-being 138 

xiii. Sense of touch 142 


I. On Sensation and the Sensible — 

Chap. i. Purpose of sensation, importance of hearing - - 145 

iL The organs of sense, theories of vision - - - 150 

iii. The diaphanous, theory of colours, colour and 

mixture 157 

• • • 



Chap. iv. Nature of flavours, flavour and moiBture, Benae of 

touch 164 

V. Nature of smell, function of smell, smell and 

respiration, smell and nutrition - - - 171 

vL Sense and magnitude, medium of sensation - - 180 

vii. Fusion of sensations, co-ordinate sensations, simul- 
taneity, limits of perception .... 186 

IL Oh Mjbmobt and IUoollbotion — 

Chap. L Memory and time, memory a picture, memory and 

phantasm 196 

ii. Association of ideas, processes of memory, recollec- 
tion 203 

IIL On Slxspino and Waking — 

Chap. L Sleep and sensation, sleep and nutrition - - 213 

ii The central sense, form and matter, movements 

in sleep - - 218 

iii Afiiw>^»1 heat and sleep, food and sleep, the blood 

and sleep 224 

lY. On Dreams — 

Chap. i. Dreams and illusion 231 

ii. After-images, the eye and the mirror, illusion - 235 

iii Movement in dreams, imagination in dreams, 

dreamless sleep 240 

V. On Prophicct in Slbsp — 

Cliap. i Prophetic dreams 247 

ii Power of prevision, interpretation of dreams - 251 

VL On Lonokvitt and Shortness of Life — 

Chap, i The tenure of life 256 

ii. Causes of destruction 258 

iii. The perishable and imperishable . . - - 260 

iv. Length of life in plants and animals - - - 262 

v. Causes of long life 264 

vi. Comparative longevity - 267 



VII. On Youth and Old Agk, and on Lipe and Death — 

Chap. L Life and Senfiatiou 270 

ii. Unity of the life-principle 273 

iii Development of life 276 

iv. Congenital heat 279 

V. Extinction and exhaustion 281 

vi Begulation of animal heat 284 

VIII. On Respiration— 

Chap. i. Purpoee of respiration 286 

ii. Aquatic animals 288 

iii Lungs and gills - 290 

iv. Theory of Democritus, heat and respiration - - 293 

V. Plato's theory of circular movement ... 296 

vi Pythagorean theory, respiration and nutrition - 298 

vii. Theory of Empedocles regarding respiration - 299 

viii. Animal heat, regulative function of respiration - 302 

ix. Control of temperature, respiration of insects - 304 

X. Function of lungs and gills 307 

xi. The windpipe and epiglottis .... 309 

xii. Kespiration of whales and dolphins - 31 1 

xiiL Lungs and the supply of blood .... 313 

xiv. A theory of Empedocles, effect of environment 315 

XV. Physiology of heat-regulation - - - 318 

xvL Position of heart and gills • - 319 

xvii. Birth and death 321 

xviii. Causes of death 324 

xix. Inhalation and exhalation 325 

XX. Movements of the heart 326 

xxi. Contraction and expansion of lungs, conditions of 

life, natural history and medicine, ... 328 

Bibliography 331 



The Soul and Life. 

Abistotle's theories regarding the structure and functions 
of the *8our are found chiefly in the De Anima^ 
and the tractates collectively known as the Parva 
Natv/rcUia} These works belong to that part of the 
corpus which deals with what Aristotle understands 
by Physics, i,e. the world of corporeal substances, sub- 
stances subject to motion and rest. Mathematical bodies, 
not being subject to motion, are excluded. Soul is 
ascribed to all bodies whose principle of motion is 
inherent in their own nature. In other words, it is to all 
organic bodies that Aristotle applies the term ; to him the 
word ' soul ' is synonymous with the word ' life.' Accord- 
ingly, the higher phenomena of mental life are included 
among the vital activities. Aristotle, therefore, regards 
Psychology .from the point of view of Biology. 

The philosopher of Stagira is known chiefly through his 
works on Logic, Metaphysics, Ethics, and Politics. It 
was mainly through these disciplines that he dominated 
the intellectual development of the western world down to 
the era of modem science ; and yet his writings on Physics 

' See note, TranBlation, p. 1.* 'See note, Translation, p. 145. 



occupy more space (taking as a standard the Berlin edition, 
which contains, it is true, some spurious treatises) than all 
the other treatises put together. Suidas, indeed, gave him 
the title of the " Secretary of Nature," while Dante, who 
was conversant with the speculative or practical side of 
his philosophy, called him " the master of those that know." ^ 
/ The studies of Aristotle appear to have been concerned 
chiefly with the phenomena of nature, whose processes it 
was the primary function of his philosophy to explain. 

The thing which most astonished Athenaeus (one of the 
most learned Greeks of the Ptolemaic era) in his reading of 
Aristotle's works, was the Stagirite's wonderful knowledge 
of animal life. He says in the Deipnosophists : " Aristotle, 
my dear Democritus, about whom the sages incessantly 
talk and whose accuracy they constantly praise, is a marvel 
to me. I should like to know from what Proteus or 
Nereus of the deep sea he learned what fish do, how they 
sleep, how they live. For he has told us in his writings 
all about these things, so that he has become, in the words 
of the comic poet, * a wonder to fools.' " * 

In contrast with this trivial, popular conception of 
Aristotle's work, I quote here Aristotle's own words touch- 
ing his attitude towards the various spheres of scientific 
inquiry, words very significant for their singular catho- 
licity. "By way of introduction we observe that 
some members of the universe are imgenerated, im- 
perishable, and eternal, while others are subject to 
generation and decay. The former are excellent 

^ II maestro. di color che saimo. In/emo, iv. 131. 
^ Deipnowphiatcte, Bk. viii., chap 47. 


beyond compare and divine, but are less accessible to 
knowledge. The evidence that might throw light on them 
and on the problems which we long to solve respecting 
them, is furnished but scantily by sensation, whereas 
respecting perishable plants and animals we have abun- 
dant information, living as we do in the midst of them, 
and ample data may be collected concerning all their 
different varieties if only we are willing to take sufficient 
pains. Both departments, however, have their special 
charm. The scanty conceptions to which we can attain 
of celestial things give us, from their excellence, more 
pleasure than all our knowledge of the world in which 
we live ; just as a half glimpse of persons whom we love 
is more delightful than a leisurely view of other things, 
whatever their number and dimensions. On the other 
hand, in certitude and in completeness our knowledge of 
terrestrial things has the advantage. Moreover, their 
greater nearness and affinity to us balance somewhat the 
loftier interest of the heavenly things that are the objects 
of the higher philosophy. Having already treated of the 
celestial world, as far as our conjectures could reach, we 
proceed to treat of animals, without omitting, to the best 
of our ability, any member of the kingdom, however 
ignoble. For if some have no graces to charm the sense, 
yet even these, by disclosing to inteUectual perception the 
artistic spirit that designed them, give immense pleasure 
to all who can trace links of causation and are in- 
clined to philosophy." ^ 

^ Aristotle, On the Porta o/AnimcUa, tranalated by Ogle, London, 1882, 
p. 16. 



Aristotle regards the physical world as divided into two 
realms (the later and now obsolete division into three 
kingdoms: animal, vegetable, and mineral, is due to the 
alchemists) : ^1) » the organic world (ra IJu^vxa) ; and (2) 
the inorganic world (ra a\lruxa). The characteristic mark 
of the organic world is the possession of soul (ylri/x^), by 
virtue of which it is endowed with the power of self -move- 
ment. Its development and transformations are due to this 
native soul-force or life. life is the imiversal form of 
organic activity; sensation and the various elements of 
consciousness are specific forms. Nutritive life and mental 
life are different manifestations of a single psychical power, 
the latter representing a higher stage in the evolution of 
y{ri/X^. * life,' or the inherent capcu^ity of a thing to effect 
changes in itself, has several meanings. Whatever 
possesses any of the following capcu^ities is said to 'live', 
(1) reason; (2) sensation; (3) local movement; (4) in- 
ternal movement or transformation, viz. nutrition, growth, 
and decay. The last power is common to all living things, 
and is the basis for the further development of the higher 
powers. These various forms of self-movement are 
identical with the different types of life. The lowest and 
least complex of all the forms is the threptic or vegetal 
life manifested in the functions of nutrition, growth, and 

Aristotle conceived of Nature's processes as moving 
without a break in an ascending scale from the inanimate 
world to the most complex forms of animate existence.^ 
Naiura nihil facit per saltwrn. There is an unbroken 

1 QL Hist. antm. 58864; Depart, anim. 681a 12. 


continuity in terrestrial life. The initial form of this is 
found in plant-life. The plantK)rganism is simpler than - ' 
any other, its functions are confined to nutrition and 
reproduction. The function of growth or vegetation in 
plants is analogous to the nutritive functions in higher 
organisma A process of conversion and assimilation is 
carried on in both cases and by analogous organs. Roots 
are analogous to the mouths of animals,^ or, as Aristotle 
elsewhere employs another analogy, they are like umbilical 
veins that take in nourishment from the earth as the 
embryo is maintained by its attachment to the uterus.^ 
Plants, furthermore, as Aristotle observed, exhibit the 
morphological tendency to develop their organs at the 
extremities, while animals tend to develop theirs at the 

The transitional form of life in proceeding from plants 
to animals, or from phenomena of growth to phenomena of 
sensation, is found in the Zoophytes. There are some 
marine animals, Aristotle says,* concerning which it is 
difficult to say whether they are plants or animals, for 
many of them grow on rocks and die if detached. To 
these transitional forms belong the sponges, holothurians, 
star-fishes, acalephae (sea-anemones), and sea-lungs.^ All 
of these possess a low degree of sensation, and some of 
them are incapable of movement. Aristotle's reason for 
classifying sponges amongst animals seems to have been 

1 Dean. 41263. 

*Cf. 2>e part, emim, 660a 20, 686635 ; De gener, anim, 745623. 

* Cf. 6. H. Lewes, Aristotle, pp. 187, 192. « Hist, antm. 5886 12. 

* Gf. Ogle, Ari&totU on the Parts of Animals, p. 226. 


that they possess rudimentary sensation,^ although they 
are mcapable of locomotion, and can be regarded only 
as belonging to the initial stage of animal development. 
Nature completes the transition from plant organisms to 

> ^ animals proper by an increased or added €k5tivity of the 
soul, in which are manifested Jthe further phenony^na of 
sensibility, with which desire is associated, and desire 
demands locomotion. An animal soul is a more complex 
and more highly developed form of the original life- 

While we in modem times, in popular language at least, 
differentiate the life found in the plant- world from that 
which is found in the animal- world (though the boundary 
between these two is not exactly defined) by the obvious 
distinctions of 'vegetable' and 'animal' life, Aristotle 
regards them as fundamentally the same. He looks upon 

^ the functions of sensation, locomotion, and conceptual 
thought as a higher development of the vital principle 
found in plants. We distinguish between sensation and 

-^ conceptual thought without ascribing them to a different 
mind, as Plato did ; but Aristotle goes further and maintains 
that not only these, but also the function of nutrition, are 
due to the same unitary vital force. It is, however, a* 
distinctly marked stage that nature makes in the develop- 
ment of the vital principle when sensation is exceeded and 
rational thought is reached. This new phenomenon is 
confined to man, and is the last stage in the evolution of 
y^tvyii* Soul is, therefore, in the opinion of Aristotle, the 
unity in which the principles of life, sense-perception, and 

^i7»0<. afitfii.487&9. 


thought are embraced. These taken together form an 
ascending series in which the higher form always includes 
and presupposes the forms below it.^ 

The function of nutrition furnishes the basis of ' 
sensation ; sensation furnishes the basis of conceptual 
thought The lower functions exist teleologically for the 
higher. Man, consequently, is the apex of creation, ) 
because all forms of life terminate in him as the complete 
development of what is contained implicitly and im- 
perfectly in the lower organisms. These forms of life or 

soul, as we have enumerated them, are the following: 

1. The nutritive or vegetal life. 

2. Perceptive power or the life of sensation. 

3. Creative power or desire attended by the capcu^ity 

of local movement, sometimes caUed by Aristotle 
the kinetic souL* 

4. The life of intellect or reason, called the logistic or 

dicmoetic souL 

These, as I have pointed out, are various manifestations ^ 
of a unitary life. The soul is not divided into separate ^'^ 
faculties or parts. In every organism it is a unit. In this 
respect Aristotle differs widely from Plato. The division 
of the soul into kinds is only a convenient abstraction. 
The soul's powers are not topographically separable as 
in the Platonic psychology. The difference in kind is 
merely a difference in mode of operation and expression, 
determined by the nature of the materials with which the 

1 Dt an, 434a 23 ff. <2>e an. 413a 23, 4136 12—31. 

•Dean. 413627. 



soul is concerned. Thought, growth, and decay are modes 
of the single life of the organism. Aristotle, therefore, 
conceived his entire psychology under a biological form. 

Everything that moves itself contains a duality of 
moving principle and thing moved, i.e, a duality of ' form ' 
and ' matter,' to use Aristotle's metaphysical terminology. 
Every living thing, a plant no less than a man. is a 
composite being (avvoXov), viz. a composite of soul and 
body. The soul is the cause of motion and change, and 
is therefore the ' efficient cause ' ; it is further that which 
determines the form or individuality of the organism, and is 
therefore the ' formal cause ' ; it is also the end for which 
the body exists, and is, for this reason, the 'final cause.' 
The body is the 'material cause' or condition of the 
composite, while the soul represents all of the principles of 
activity in the organism. Soul is defined by Aristotle as 

_ the "entelechy or complete realization of a natural body 
endowed with the capacity of life." ^ The soul or vital 
V principle is not itself corporeal, although it is inseparable 
from the body, as form is inseparable from matter.^ Soul 
and body are not distinct things that do or can exist apart. 
<* Their separation is only notional. They no more exist 
apart than do concave and convex. 

(^ Soul is to be found in every part of the body. This is 

observable in the case of graftings, where the entire parent 
form can be reproduced from a section. Insects live for 
some time after bisection, but they do not continue to live 

^Dean. 412a 20, 4126 5. 

* This does not apply to the Prime Mover as pure ' form.' The relation 
of the active reason to the body is discussed below in the chapter on 
Reason (chap. viii.). 


on indefinitely, because they lack organs for maintaining 
life. As we go up the scale of living forms, this division 
of soul throughout the body becomes less and less marked ; 
the higher the order of life the greater the centralization. 
In the case of animals, the body consists generally of three 
main divisions : the head, thorax, and abdomen. Aristotle 
points out ^ that if a wasp's head is cut off, the thorax and 
abdomen continue to live for a time ; if the abdomen is cut 
off, the head and thorax continue to live. In other words, 
the part which is conjoined with the thorax exhibits this 
continuance of vitality. For this reason it would appear 
that the anatomical centre is also the life-<^ntre. This 
is, furthermore, on a priori grounds the best and 
most advantageous position. It is reasonable to suppose, 
therefore, that nature in her wise economy ^ has employed 
this central section as the vital centre. 

This view, however, is not merely derivable from rational 
considerations, but is also supported by grounds of obser- 
vation. The life-centre may be localised not only in the 
thoracic region, but specifically in the heart. For this 
statement Aristotle adduces the following arguments: 
(1) disease of the heart is the most rapidly and certainly 
fatal ; (2) psychical affections, such as fear, sorrow, and joy 
cause an immediate disturbance of the heart ; (3) the heart is 
the part which is first formed in the embryo, and, as he 
says in the History of Animals? it appears in the egg of the 
chicken on the third day of incubation as a red spot (the 

^ Dejuvent, 468a 21 ; De part, anim, 667622 ; De rtspir. 479a 6. 
'Cf. Leibniz's "choix de la Sagesse," Princ, 11; also Nouv, E99, 11., 
ch. xxi, 13, Langley's tranalation, p. 183. 
*i^i«(.amm. 561a 612. 


punctiim aaUena of later writers) which palpitates and 
whose movements are those of an organism endowed with 

Ihe. hfgTti^jf|_ftti^.nnflo the phyniolggag ^ and psychic al 
centre of m£UQ. In as much as Aristotle identifies life 
with soul, it is a matter of consistency for him to place 
the seat of the soul in the vital centre. He rejects the 
doctrine of Plato and Diogenes of Apollonia, who re- 
garded the brain as the organ of mind. To Aristotle the 
brain is merely a regulator for the temperature of the 
heckrt; the brain is bloodless and cool, and the blood 
and warm vapours from the heart rising to this are 
lowered in temperature. By this physiological device, 
conjoined with the service of respiration, Aristotle sup- 
poses that the system is maintained in a heat-equilibrium. 

The material element in which the sonl is immediately 
incorporated is heat or fire, but the soul is not identical 
with this, as Democritus thought. Nor is the vital heat 
ordinary fire, but some subtle principle analogous perhaps, 
as Ogle says,^ to that imponderable and hypothetical 
matter of the physicists known as Ether. In accordance 
with his theory, Aristotle was naturally forced to attribute 
vital heat to plants and the cold-blooded animals, but his 
grounds for this position are not to be found in any of 
K^" the extant worka He had, of course, no knowledge of 
the chemical elements of oxygen and carbon. The vital 
caloric of the body is kept up by food which serves as 
fuel This heat which, according to Descartes, is produced 
by fermentation or, according to Haller, by friction between 

^ Ariitotle, On Youth emd Old Age, trana. by Ogle, Introd. p. 9. 


the blood particles, is being constantly generated and 
ccMistantly given off. To prevent an excessive production 
of animal heat, the respiration of the lungs, along with 
the cooling function of the brain above referred to, is the 
most important means. In the case of fishes the same 
thing is accomplished by bathing their gills in a medium 
of lower temperature than their bodiea 

As to the cause of the natural and normal extinction 
of life, Aristotle says it is due to loss of balance in 
the production and consumption of heat. The heat is 
gradually extinguished when the generation of heat, as 
in old age, is not adequate to the demand of consumption. 
The length of life in any animal varies according to its 
material constitution and the suitability of its physical 
surroundings. As a general rule, animals or plants of 
great bulk^ are long lived; small ones are short lived; 
sanguineous animals live longer than those that have no 
blood ; and a long period of gestation is usually correlated 
with long life. The purpose of the threptic soul is nutri- 
tion and reproduction. The food which is taken up into the 
vegetable or animal organism and nourishes it, has its 
end not merely in the continuance of the individual's life, 
but has a higher end in the formation of another life of 
like kind by reproduction. The function of the individual 
is not merely to live, but to reproduce and so to maintain 
life's continuity. 

^ On the longerity of animals, see translation, pp. 266>205. 



The Faculties of the Soul. 

Plato conceived three psychological elements — which cor- 
respond roughly to cognition (i/oirr£/coi/),£eeling (e-TriOujjL^ucop), 
and conation (Ou/uLoeiSe^) — in terms of ethical value. Cogni- 
tion has the highest worth, and conation stands next in 
rank. Feeling has the lowest moral value. These are 
not faculties or Svvafiei^ of the soul, but ' parts ' (fiepri)- They 
consitute real entities in the psychophysical whole, just 
as the three divisions of government in the state have 
separate and real existence. The two lower parts, how- 
ever, have no share in pre-existence or immortality.^ These 
are never referred to as powers or faculties (Supa/jiei^). 

The term * faculty ' is applied by Plato to certain pro- 
cesses of the soul which are determined by the object to 
which they are directed or the results they accomplish. 
Sense-perception {010-6910-19), opinion (S6£a), and conceptual 
knowledge (eTrtoiniiuLri) are described by Plato as * faculties.' * 
The faculties depend upon the reciprocal relation between 
subject and object. The ' parts ' of the soul (the Platonic 
' parts ' are the historical predecessors of the post-Platonic 
'faculties*), on the other hand, are entities, situated in 
various regions of the body, and denote certain qualitatively 
distinct types of psychical life, arranged on a scale of 
ethical value. The seat of reason is in the brain, the 
topographically higher region being correlated with the 
reason's higher worth ; the conative part is situated in the 

iCf. Siebeck, OeschichU der Paychologie, Th. I., Abth. i., p. 203. 
^Protagaraa, 330A. 


thorax, more particularly the heart, so as to be the con- 
venient ally of the reason in the ethical regulation of the 
individual's life;^ the feelings and appetites are situated 
in the abdominal cavity, their upper boundary being the 
diaphragm and their chief organ the liver. 

Plato's entire psychology, in which the soul's parts 
are separated into existentially distinct units with distinct 
anatomical organs, is ethico-teleologically determined. 
Aristotle's psychology, on the contrary, is biologically 
determined; the soul is a unitary life functioning in 
distinct modes or faculties.^ It is a single indivisible mind 
expressing itself in nutrition, sense-perception, imagination, 
memory, reasoning.^ To Aristotle there is a thinking 
substance, a 'soul,' which possesses certain distinct capa- 
cities. In the term 'faculty' or 'potentiality' there is 
implicit the idea of latent or possible activity. Further, 
SvvafjLig conveys the notion of being native and not acquired 

In their action, manifestation, or processes, the faculties 
of Aristotle are merely a convenient classification of 
psychical phenomena into groups.* They correspond to^ 
the fundamental divisions in organic life — plant, brute, 
man. The psychological faculties or functions, therefore, 
represent the several stages in the development of the 
forms of organic life. The soul operates in every particular 
organism under one or other of these forms, viz. it effects 

^Timaeu8, 70Aff. 

* See the chapter on the Creative Becuon, chap. viii. 
*Cf. Wundt's OrundzUge der physiohgischeii Psychologies 4te Aufl. Vol. 
L, pp. 10 ff. 


nutrition, or it experiences sensation, or it causes loco- 
motion, or it thinks, or in the highest organism it acts 
under all four forms. Sometimes Aristotle speaks even of 
five faculties, viz. the nutritive, sensitive, conative, loco- 
motive, and rational;^ again he speaks of four,^ and at 
other times of only three, owing to the identification of the 
orectic and sensitive powers.^ 

It is evident from this that Aristotle laid no great weight 
-\ on any fixed enumeration of the faculties, and he expressly 
says that from one point of view these * parts of the soul ' 
appear to be indefinitely large in number.* If we regard the 
fimdamental aspects, therefore, under which the soul mani- 
fests itself, Aristotle defines it as that principle by which 
we live, have sensation, and think.*^ The vegetative or 
threptic life is confined to the phenomena of nutrition 
and reproduction® ; sensitive life is confined to the pheno- 
mena of cognition when the object is spatially and 
temporally determinate, i,e. an individual thing; rational 
life is concerned with phenomena of cognition when the 
object is an universal or an abstraction.^ The stages in the 
development of organic life are differentiated from one 
another in terms of psychical activity; plants live and 
reproduce; the lower animals live, reproduce, and have 
sensation ; man lives, reproduces, has sensation, and reasons. 
Each higher stage includes within itself the fundamental 
functions of the lower stages. Aristotle's view of 

iDean. 414a31. >2)e an. 413612. > 2>e an. 431a 14. 
« De an. 4d2a 24. * />e an. 414a 12. 
^De an, 413a 22 ff., 415a25 ; De gener, anim, 740630. 
fDe an. 417&22; AnaL post. 87637; Dt imom. 4586 Iff.; Metaph. 
9996 27 ff. 


the physical world may be presented schematically as 
follows : 

Organic world Inorganic world 

(rd f/iiffvxo) {"rdi dxl/vxa-) 


Vegetaole life Animal life 

Nutrition | 

and raproduotion). 

Lower animals Man 

(Nutrition, reproduction, (Nutrition, reproduction, 

and sensation). aenaation, noStio life). 


Nutrition and Repboduction. 

Nutrition is the simplest form of organic movement. 
Every living thing must have the power of nutrition, for 
organic development is not possible without food. All 
sensation and noetic activity presuppose this nutritive 
faculty as their basis. To use Aristotle's phraseology, those 
organisms which assimilate form and matter at once and 
are incapable of assimilating form without matter, live 
exclusively a vegetative life. In other words, the process 
of vegetal growth is a physical process, i.€. the organism 
takes up certain corporeal substances into its physical 
structure, and it does so through the agency of an inherent 
psychical or vital principle.^ 

In sensation, on the other hand, the form of the object 
(without its matter) is taken up by the agent. The signifi- 
cance or form of the object is assimilated by sensation ; 
the matter of the object is assimilated when the nutritive 

1 2>e an. 4246 1. 



power appropriates it. Indeed, the whole of the psychical 
life is carried on by means of assimilation. The threptic 
power by the instrument of heat converts foreign substances 
into forms similar to organic structures, and into these 
structures the substances are then absorbed. Analogically 
the data of sensation and experience are assimilated into 
the concept, and the qualities of things are assimilated into 
the forms of sense-perception. The entire process of 
psychical life is a process of conversion, in which objects 
are reduced to terms of likeness with the subject or 

There was a pre- Aristotelian controversy as to whether 
nutrition is effected by the like or the opposite.^ Aristotle 
says that assimilation implies indeed original opposition, 
but the unlike undergoes in digestion a process whereby it 
is rendered like, and as such is taken up by the organism 
as part of its physical structure. In their ultimate phases, 
therefore, the like is nourished by like. Such is Aristotle's 
conclusion on this academic question of the Early Greek 
schools, a discussion which had concerned itself mainly 
with Epistemology, i,e, with the question whether the per- 
ception of a quality is due to the possession of a like or an 
opposite quality in the agent. 

Food after it has been concocted and assimilated becomes 
the means (1) of nourishment, (2) of growth, (3) of 
reproduction. It nourishes in so far as it sustains the life 
of an individual and enables it to persist ; it causes growth 
in so far as it acts quantitatively and enables the 

^ Dt an, 416a25 ; cf. also on the Empedoclean and Anazagorean theories 
of senBation, translation, pp. 35, 150, 166. 


individual to attain its normal mass in development;^ it 
makes reproduction possible by conversion of a part oi'7 
the food into seminal matter.* One must observe three ^ 
main facts in nutrition, viz. the cause, the object, and the 
means. The cause is the elemental soul or threptic energy ; 
the object is the body animated by the soul ; the means is 
the food. Food, however, can maintain the life of an 
individual only for a limited time. The continuity of 
life is accordingly provided for by the deposit of semen, 
which contains potentially all the elements of the organism ; 
thereby the propagation of a life similar to that of the 
parent is 8ecurecL» This is the highest and most important 
service of the threptic power, because it gives to perishable 
creatures an approximate immortality by perpetuating the 
species, and this is what every creature instinctively aims 
at. It is the final cause of every creature's natural lif e.^ 
All of nature's activity is purposive. Food is utilized for 
specific ends and in specific ways. No single substance is 
adequate for the nourishment of a physically complex body, 
and every organic body is complex. Even the lowest 
organisms, plants, employ various substances for their 
nutrition. Food, in as much as it is the material for the 
formation of body, must contain all the body's substances. 
Food, must consequently, be multiform. There is, however, 
one element in food which is more nutritive than any other, 
viz. the sweet. It is this element in edible things that is 
mainly causative of growth, and Aristotle makes a curious 

1 De an. 4165 10 ff. > De gener. anim. 725a 15 ff. 

*Gf. Aristotle, On the Parts 0/ Animals, tr. by Ogle, pp. 239, 240. 
«2>e on. 415a 29. 



<- use of this element to explain the relative longevity of 

bees.^ Fat is to be classified amongst sweet substances. 

Food undergoes no process in the mouth beyond that 
of mastication.^ Aristotle knew nothing of salivary glands, 
yet mastication, though not itself a digestive process, is a 
necessary preliminary to digestion. From the organ of 
seizure and mastication the food passes to the stomach, 
where it undergoes what Aristotle calls concoction. This 
is accomplished by animal or psychical heat, a form of heat 
which in its vivifying power differs from ordinary heat 
and is supplied mainly from the spleen and liver. The 
solid and indigestible portions pass off by the lower bowel, 
while the fluid portion,* which alone is employed in 
nutrition, is absorbed by the blood-vessels and intestines. 
The stomach and intestines are to animal organisms what 
the ground is to plants ; ^ the roots as channels of nourish- 
ment for the plant correspond to the blood-vessels in the 
animal. The veins have exceedingly fine invisible open- 
ings such as the pores in unglazed pottery, and these 
minute openings permit the nutritive fiuid to ooze through 
into them, and by them it is carried from the mesentery to 
the heart. Their content is not yet blood, it is an in- 
completely prepared serum (?x«p).^ In the heart, the 
warmest organ of the body, to which this serum is now 
immediately carried from the mesentery by the veins, it is 
re-ooncocted and converted into blood. It is then ready for 

^ De long, et hrev. vit, 467a 4. 

* D€ part, anim, 650a 10 ff. 

' De 9omno, 466a 30 ff. ; De part, anim, 6516 5 ff. ; De gener, anim, 7266 2. 

^ De part, anim, 678a7 ffl 

" Hist, anim. 621a 12 ff., 62162; Depart, anim. 661a 18. 


assimilation into the organs, for building up their waste, 
and for adding to their growth. The amount of blood 
thus generated is very small in proportion to the materials 
consumed, otherwise the body would grow to enormous 
bulk. The blood in its final state of concoction is carried 
by the arteries and veins from the heart to all parts of the 
body. Each organ assimilates such elements as are 
adapted to its growth. The process of nutrition goes on 
most actively during sleep.^ Such parts of the blood as 
cannot be utilized in organic anabolism are excreted in the 
form of sweat, bile, and nature's various means of relief 
through waste, while surplus nutritious matter takes the 
form of excess fat, seminal deposit, nails, hair,^ and other 
masses whose quantitative permanence is unnecessary for 
the maintenance of life. 

The two fundamental concepts with which Aristotle's 
entire philosophy operates, viz. form and matter, or 
actuality and potentiality, are derived from his observation 
of organic life. Potential matter in the organic world is 
being constantly transformed by an inherent life-movement 
into significant structures, and a formative or psychical 
principle is constantly active in converting passive matter 
to definite ends. Without the soul the body is motionless, 
and the organs of the body are organs only homonymously* 
— a dead hand is only the homonym of a hand, it has the 
name of a hand without its significance or function. All 
life (not only what is modemly understood by vital 

^ Dt ttomno, 455a 1. 

* Cf. Aristotle, On the Parta of Animals, tr. by Ogle, p. 202. 
Dt gener, anim, 735a 8 ; De an. 4126 14, 21. 


phenomena, but aU rational life) is a form of motion, of 
which there are several varieties : yh^^i^, €&^i^, aWoiwtri^, 
if>opau The most elementary form of organic movement is, 
as has been said, growth {aS$n(ri^)} The soul is in every 
part of the body, and, although not itself corporal, it is 
inseparable from the body. This diffusion of soul is more 
apparent the lower we go in the scale of animate exist- 
ence.' Organic centralization increases in direct ratio with 
the complexity of the organism, but even in the lowest 
forms of animal life there is a certain degree of centraliza- 
tion, lowest of all in the plants. The only form of life 
which is separable from the body is that of the active 
reason, and even this, so far as its real content is concerned, 
is an * entelechy of the body.' 

Heat is the soul's material substrate, in which the soul is 
immediately incarnate. The soul is not itself heat. " Birth 
is the original suffusion of the nutritive soul with heat, 
and life is the maintenance of this heat." ^ The manner in 
which this heat is maintained by the fuel of food through 
concoction has been already described. Not only must the 
body have this heat in order to live, but the heat must be 
regulated and kept within normal limits. There must be some 
physiological provision for the reduction of temperature ; 
otherwise the fuel in the stomach would constantly generate 
heat to excess, especially during the process of digestion. 
Mech€uiism for reducing temperature in the pulmonate 

» P^y«. 260a 25 flf. 

^Dtan. 4116 20,4136 20. 

^Dt reapir. 479a 29. Birth or genesis means for Aristotle not the 
separation of the young from the mother's body, but the process of 


animalfl is famished by the longs ^ and brain, in aquatic 
animals by the gills. Death comes to all organisms when 
the supply of vital heat fails ; the organs of nutrition and 
respiration become through lapse of time incapable of 
supplying and regulating this heat, it being both inade- 
quately generated and inadequately controlled, and so 
" the fire of life is snuffed out/' ^ When the basal psychical 
function ceases, the higher life of mind is no longer possible, 
for the soul is not divided into parts, but is an unit. 



The im mediate instruments for the apprehension and in- 
t erpretation of the external world are the perip heral sense- 
or gans. Sensation, which marks the boundary between the y 
animal and plant wor]^ is explained by Aristotle as a 
form of moiio n^V^!^s!j^^ change * (aWolaxrig) in a 

sense-organ. The sense-process and the sense-object are \ 
one in the actual sensation. Sound and hearing, for ^ 
example, although notionally distinct, are identical in the 
act of sensation.^ The sense-organ is potentially what the 

^The organs known to as as 'lungs' were regarded by Aristotle as the 
right and left halves of an azygoos organ. Consequently he always speaks 
of ' lung ' in the singular. He found the organ to be actually single in 
certain snakes {Hist, anim, 508a 28 ff.), and when it is double the two 
divisions have a common outlet in the trachea. I have, however, in con- 
formity with the demands of English speech, translated his singular by a 
ploraL See the translation, pp. 286 ff. 

•Derwptr. 479a 18. 

*De 9omno, 45964 ; Phys, 247a7 ; De an. 416624. 

« De an. 424a 25 4256 26, 418a 1. 



sense-object is actually. To make a further use of Aristotle's 
terminology, the organ assimilates the significance or form 
of a thing without its matter.^ life rises above the uncon- 
scious process of nutrition, when in sensation the external 
world is transformed into a conscious world, a world of 
meaning. The sense receives an impression or picture of an 
object, as wax receives an impression of a seal-ring without 
the bronze or gold of the ring.* The sense is thus, in a way, 
identical with the object ; it differs from the object, how- 
ever, in its mode of being. The sense apprehends a quali- 
tative element belonging to an individual,' but not the 
individual as such. 

Sensation is a process that belongs to both soul and 
body.* The sensation itself is psychical, but its instrument 
is physical The eye and vision are related to each other 
as matter and form.* Vision consists in a certain relation- 
ship or condition of harmony. Excessive stimuli destroy 
this harmony, just as the harmony of strings is destroyed 
by striking them violently.® 

Without contact there can be no action of one thing 
upon another. This law, which applies to the whole of 
nature, necessitates the assumption of a continuous medium 
from object to subject, for there must be some sort of 
contact if the object of sense is to affect a sense-organ. A 
medium is further necessary because no sensation results 

^De an, 424a 27, 426a 26, 431626. 

*I>e an, 424a 19S.; De menu 450a 30. 

*Anal. post. 876 28, 100a 16 ff. ; Z>e an, 424a 21 ff. 

* De samno, 467a7 ; De aenMu, 436a6 ; />e an. 402a 4ff. 
^ Dean, 4126 18 fE: 

• De an. 424a 32. 


when organ and object are in immediate contact.^ The 
intervening medium, however, is in contact with both 
organ and object and transmits a stimulus from the latter 
to the former, without which no sensation would result. 
The medium is different in different senses. 

In considering the subject of sensation it is necessary to 
observe, in addition to the faculty itself, three conditioning 
factors: (1) the organ, (2) the object, (3) the medium. 
There are five senses, and at the beginning of the third 
book of the De anima ^ Aristotle attempts to prove that 
this enumeration is exhaustive. 

1. Sight. 

The sense of sight is the most important for life,* 
although hearing has a higher significance for purely 
intellectual life, because of the meaning conveyed by the 
spoken word. 

a. The Organ of Sight — The psychologists preceding 
Aristotle and contemporary with him regarded the sense- 
organs as composed severally of the elements, but as there 
were for the pre-Socratics only four elements (fire, earth, 
air, and water), whereas there were five senses, they were 
in straits about a fifth element with which to pair a fifth 
sense.^ Further, they differed in the elements assigned to 
the several sense-organs. Plato, e,g., coupled vision with 
fire, whereas Democritus coupled it with water. Aristotle, 

1 De an. 4216 17, 423620 ; Dt gener, tt carr, 322622 ; Phys. 245a4. 

* Dt an. 4246 220*.; cf. also HUe. anim, 532629. 

* Metaph. 980a 21 ; De senm, 437a 5 ff. 

* Desentu, 437a 19ff. 


likewise, regards the sense-organs as composed of the 

elements, and as to the constitution of the eye he agrees 

with Democritus. The eye's power of vision is due to the 

element of water in it, the organ being m constitution 

analogous to the medium through which its stimulus is 

transmitted, i,e, a translucent medium.^ Hearing is due to 

the air immured in the inner ear. Smell is correlated with 

one or both of the foregoing elements (air and water), and 

touch and taste are correlated, perhaps, in some special 

^ manner with earth. The sense-organs are thus coupled 

\ with their media and not with their objects.* The real 

organ of vision is the pupil (Koprj)? which is within the eye 

and is composed of the element of water, and the best eye 

is the one whose proportion of water is best adjusted.* In 

order that light may penetrate to the interior, it is 

necessary that the eye be translucent, and water, because 

it is more easily fixed and kept in place, is better adapted 

to this purpose than air would be.*^ The water of which 

the pupil is composed is derived from the brain.® Aristotle 

^ De an, 4246 28 ff.; De aensut 4385 3ff.; Depart, anim. 647a 2ff. 

' The account of the sense-organs given in the Parva NcUuralia ( De 
aensu, 4386 3 ff.) differs somewhat from this {e,g, smell is correlated with 
fire). The discrepancy is to be explained (of. translation, pp. 96, 150) by 
the fact that in the Parva NcUurcUia Aristotle is reporting corrent opinions 
(evidently so in his description of smell as a smoke-like exhalation), or it 
may be accounted for by the theory (held by Torstrik, but impossible to 
establish) that the De $en9u is an earlier treatise than the De anima, 

* De part, anim. 653625; Hist, anim, 491621; De aeMu, 438a 16; De 
an, 425a 4. 

^ De gener, anim, 780a 22 ; De senau, 4386 5 ff. 

^ De senm, 438a 10 ff. Cf. Theophrastus, De sewm, 39. Diogenes of 
Apollonia believed air to be the essential element in the composition of all 
the senses. 

• Hist, anim, 492a 21, 495a 11 ff. 


speaks of three oonduits or xopoi leading from the eye to 
the farain, which may refer to the ramvs opkUuilmicus, 
opticus, and ocvJ<mu)toriii8, although he did not, of course, 
regard these as nerves, of the function of which he had no 
knowledge whatever. The optic nerve he recognized as a 
duct, and noted the fact that the eye of the chameleon is 
continuous with the brain.^ The term ir6po9 is, indeed, 
used later on to mean nerve.^ The connection, however, 
here referred to by Aristotle is not a connection between 
peripheral and central organ. The duct between eye and 
brain serves only physiological purposes, and the connec- 
tion is, strictly speaking, not with the brain at all, but only 
with the empty occiput and the vascular membrane 
surrounding the brain.' The brain, as has been pointed 
out, is not the central sense-organ. The peripheral organs 
of sight and hearing are not only connected with the 
vascular membrane of the brain, but they are also con- 
nected with the heart,* which is the sensory centre as it is 
also the vascular centre. Because the eye is connected 
with the brain and derives its water from that source, it is 
moist and cold like the brain.^ Its power of vision is due 
to the translucence of its composition.® 

6. The Object of Sight — The object of vision is the visible^ 

^ Hist, anim, 492a 21, 495a 11 ff.; De gener. anim. 743635. 

* Galen, Dt U9u part, m. 12, quoted by Ogle, Aristotle On the Parts of 
Animals, p. 176, note 19. 

* De part. anim. 6566 16. 

^ffist. anim. 495a 4, 514a 18 £; De sgnsu, 439a 2, 444a 10 ; Depart, 
anim. 6526 16, 6566 24 ; De juvent. 469a 10 ff.; De gener. anim. 7436 25, 
781a 20. 

* De gener. anhn. 744a 5ff. * De sensu, 438a 12. 
^De an. 418a 26, 422a 20, 424a 10. 


and the invi8ible,for opposites are subject-matter of the same 
faculty of perception and of the same science.^ The visible 
includes colour and certain phenomena which Aristotle 
calls anonymous, whose characteristic is brightness.* Colour 
is a qualitative accident that has the power of exciting or 
moving a diaphanous medium.' Vision consiste neither in 
an efflux from the visible nor in an image thrown off by the 
visible, as the Atomists and Empedocles^ supposed, but in 
the excitation of a translucent medium by means of colour 
and in a qualitative stimulation of the organ of vision by 
means of the medium so affected. The diaphanous medi- 
ates colour, and light is that which converts the poten- 
tially diaphanous into the actually diaphanous. Colour 
sets the actually diaphanous in motion and is mediated in 
the form of motion from a remote object to the sense- 
organ. The diaphanous is not itself visible, but the colour 
with which it is charged is visible. The actuality of the 
diaphanous is light.^ The diaphanous as such is colour- 
less,^ but has the capacity of being illuminated and charged 
with colour. The colour constitutes its light in an acci- 
dental sense,^ i,e. light is no particular colour. Light is 
not somatic nor the efflux of any body ; it is not fire,® but 
depends on the presence of fire,* or is a subtle species 
of fire. As the diaphanous is actually translucent 
only in light, so colour is visible only in light. Fire, 
on the other hand, is visible in both darkness and 

^Dean, 41 la 3; Top. 10665; Metaph. 1061a 18. 

^Dean, 418a 27. 

* Top, \03b 31 ; Categ, 96 9 ; De an. 4186 1, 419a 10. 

*D^^eTuu, 438a 2. ^De an. 4186 9, 419a 11. « De an. 4186 28. 

f De MiMtt, 439a 18. » De an. 4186 14. » Top. 134628. 


light,^ for it creates for itself a translucent medium by 
difiusing light. Colour, then, is a condition belonging to 
light, as light is a condition attaching to the diaphanous. 
The diaphanous belongs to water and air, the media of 
vision, and to some extent to other bodies,^ but has na 
independent existence. It is not a substance. Colour is 
further defined by Aristotle as a quality of the superficies 
of a body in a diaphanous medium. So the Pythagoreans 
called colour a visible superficies. There are seven primary 
colours derivable from the basal colours, white and black.* 
They are : white, black, yellow, violet, green, and blue. The 
other sort of 'visible,' called by Aristotle 'anonymous,' 
consists in brightness produced by a smooth, polished 
surface, such as is found in certain fish-heads, scales, 
eyes, and phosphorescent substances.* This is not properly 
colour, but a fiery phenomenon which has the power of 
difi^ing light and creating visibility. 

c. The Medium of Sight. — The medium of sight is the 
diaphanous, viz. air and water and certain other translucent 
bodies.^ They are the media by virtue of their trans- 
parency, which belongs to them not as air or water, but 
because they possess something in common with the eternal 
empyrean.® The medium itself is neutral and colourless, 
being thus adapted to saturation with and transmission of 
any colour. Aristotle rejects the emanation theory of 
colour, and resolves it into a form of movement of a 
medium, approximating herein more closely than his 

^De an, 4186 2, 419a 23. *De seruuy 439a 20ff. 

^DesetuUt 4396 20 ff., 442a 19 ; cf. also translation, p. 87, note 2. 
* De an, 4l9a Iff.; De atnsu, 4376 5. > Dt an. 4186 6. 

*/>e an, 4186 7 ; Dt sensu, 438a 12. 


predecessors to the modem hypothesis of ether vibrationa 
Colour excites the pellucid element, which then transmits 
the colour-motion from the object to the sense-organ. This 
movement does not, however, consist in an undulatory 
process, but in a qualitative change, whose spatial propaga- 
tion is not discernible,^ and which appears to be instan- 
taneously complete. 

2. Hearing. 

a. The Organ of Hearing. — As the real organ of vision is 
composed of water, similarly the real organ of hearing 
consists of air.^ Air is immured in the inner ear and is 
immovable there, i,e, it cannot be dispersed. This fact 
enables it to detect all distinctions in communicated 
motions. We hear in water, because it cannot penetrate 
to the congenital air,' but we hear through water as through 
any other foreign body. Aristotle ascribes hearing to fishes, 
but nowhere explains how they hear, although in the 
History of Animala he devotes several paragraphs to the 
subject of sensation in the lower animals.* The congenital 
air has its own internal movements, which account for 
certain phenomena of sound, such as the hearing of sound 
when there is no external stimulus.^ A duct or channel 
leads from the ear to the rear of the brain, the occiput, 
which Aristotle supposed to be hollow and filled with air. 
This iropo^ is perhaps the external and internal meatus, or 

1 Dt HfMU, 4466 20 ff., 4386 3 ff. 

^Depart, anim, 6566 16 ; Dean. 419634, 425a 4. 

*De an. 4196 18, 420a II; De gener. anim. 781a 23. 

*HUt. anim. 632630 ff., 5336 Iff. ^De an. 420a 17. 


possibly he considered the conimunication to be established 
by the Eustachian tube, which was known to him.^ 

b. The Object of Hearing, — ^The object of heajing is 
sound.' Sound is produced by the concussion of two hard, 
smooth bodies, especially hollow bodies, in a medium.' Air 
or water may serve as a resisting body and emit sound, 
when either is so quickly and violently struck as to pre- 
vent its (air's or water's) gradual and noiseless disper- 
sion.* Each of these acts then in the same way as a hard 
body, and the adjacent water or air serves as a medium for 
the communication of the sound. The qualities of sound 
are given in terms of pitch, the extremes of which are high 
and low, or acute and grave.* The high or acute is due to 
a swift motion, and the low or grave is due to a slow 
motion. Mere sound is noise. Voice is significant sound, 
produced by an animal, and accompanied by a mental 

e. The Medium of Hearing. — The medium of hearing as 
of sight is air or water.^ These two media are in their own 
nature both colourless and soundless, but capable of trans- 
mitting colour and sound to sense-organs. The spatial 
propagation of sound is not instantaneous, but is discernible 
in time, as one can learn from the blow of an axe seen in the 
distance, the sound of which is perceived at an interval later.' 
For the transmission of sound the air must form an un- 
interrupted continuum from stimulus to organ.' The 

^ffist. anim, 491a 30, 492a 20; De part, anim, 656a 18 ; De gener, anitn, 
781a31. *De an, 418all ; De insam, 45866. 

*Dean. 4196 6 ff., 420614; De sensu, 446630; De coelo, 29la I ff. 
*De an, 420a 7. ^De an, 420a28. ^De an, 4206 25 £ 

^De an. 419618. « De «en«u, 446a 24 ff. ^ De an, ^SSOaZ, 


stimtaus must not be too sUght. otherwise it is not trans- 
mitted, nor too excessive, otherwise it disturbs the function 
of the organ.' Sensation demands a kind of proportion 
between stimulus and organ, from which there issues a 
normal organic process. 

3. Smell 

• a. The Organ of SmeU, — The organ of smell is composed 
of air or water,* of the former in the case of respiring 
animals, and of the latter in the case of aquatic animals. 
In respiring animals the organ of smell ha^ a covering, 
which is lifted in inspiration and is analogous to an eyelid ; 
without inspiring, smell is not sensed by them.» In aquatic 
animals this covering is lacking, as the analogous eyelid is 
lacking in hard^yed animals.* The nostrils, or physiological 
organs of smell, are passages ¥or inhalation and exhalation, 
and are very mobile ; whereas in the case of the ear, man 
has no muscular control of it, as most of the lower 
animals have.^ 

b. The Object of SmeU, — The object of smell is the odorous 
and its opposite.' Smell is very poorly developed in man, 
being inferior in accuracy to that of many of the lower 
animals.^ It is difficult to determine the essential qualities 
of smell, because of this imperfect development in man, and 
because smells are confused with the pleasant and un- 
plea,sant.® Smell is intimately connected with the sense 

^Dean. 420a24, 421&9, 422a26, 426a28ff. ^Dean. 425a5. 

*De an. 4216 14, 422a 1 ; De aensu, 444622. ^De stnsu, 443a3. 

*Hi9t. anim, 492a 28, 402615. 

^De an, 4216 3ff. ; Dt aensti, 4446 20ff. 

' Dt aengu, 441a 1 ; De an. 421 a 10. */>e an. 421a 12. 


of taste,^ and many smells are described in terms of analo- 
gous flavours, — eg, smells are called sweet, piquant, oily, 
harsh, pungent, terms that belong properly to taste. It is 
not, however, to be assumed that because a given thing has 
a sweet flavour it will also have a sweet smelL On the 
contrary, sweet-smeUing objects often have an unpleasant 
taste and conversely. The object of smell is described as a 
property of the dry, while flavour is the sapid-moist.^ 
That the dry property is not a smoke-like exhalation, as 
certain pre- Aristotelians held, is proved by the fact that 
aquatic animals are endowed with smell, and a smoke-like 
exhalation could not be transmitted in water.' Besides, 
this would resolve the odorous into a physical efflux, an 
explanation of sensation in general which Aristotle rejects.^ 
The odorous consists in the saturation of a medium (air or 
water) with a sapid dry element.® 

Although the sense of smell is poorly developed in man, 
he is the only animal that is capable of perceiving smell as 
fragrance, i.e. in an aesthetic way.® The lower animals have 
no appreciation of malodour as such. 

c. The Medium of SmeU, — The medium of smell is air 
or water.^ Water mediates smell for the aquatic animals.^ 
Man, however, and all respiring animals whose sense of 
smell is dependent on inspiration, cannot smell in water.^ 
Although the media of smell are the same as the media of 

1 De aenm, 4406 28, 4436 8 ; Dean. 421a 17. 

*De an. ^22a4 fL *De aensu, 438623, 443a20ff. 

^Z>e«eiwtt, 44362. * />e xeTun, 443a 3 ff. 

•De senw, 443627 ff., 445a 1. "^ De an. 419a 28 ff., 422a2. 

• De 9ensu, 443a 1 ff., 4446 5ff.; De an. 419a35, 421610. 

^ Dean. 422a2; Deaensu, 4446 lOff. 


sight, viz. air and water, these are media for sight by 
virtue of their translucence, and for smell by virtue of their 
capacity to exude dry savour. By the peripatetic Theo- 
phrastus they are called transolent {Sio<r/jLa).^ 

4. Taste. 

a. The Organ of Taste, — Aristotle's view regarding the 
organ of taste is difficult to determine. He maintains the 
doctrine that all the senses function by means of a medium, 

^' and that sensation does not take place when the sense- 
object and sense-organ are in immediate contact.^ In 
accordance with this doctrine he says the tongue is not the 
organ but the medium of taste, and yet he sometimes 
speaks in a popular way of the tongue as the organ of 
taste.^ Strictly speaking, the organ of taste is something 
more internal.* The organ proper is within the flesh and 
is fitted with a conductor to the central organ or sensorium 
{i,e, the heart).^ It is even possible that Aristotle regards 
the heart as the organ of taste and the tongue as at once 
the medium and ancillary organ.® It would seem, how- 
ever, from his general accoimt of the senses that they all 
have a medium, and that all of them have conduits from 
the peripheral organ to the sensory centre.^ 

b. The Object of Taste, — The object of taste is at once 

^ Cf. translation, p. 75, note 1. ' Cf. translation, p. 73, note 2. 

>Z>e part, anim, 647a 19, 6536 23 ff.; ffiaL anim. 533a 26; De an, 
4225 2ff. 
*Dean, 423a 2ff.; Depart, anim, 666636. ^ Deaenau, 439al, 

* Cf. Baumker, Dea Arigtotelea Lehre von den dustem und innem 
Sinnesvermi^en, p. 55. 
^ Cf. the notes on duct or T6pot above, under the organ o/aight. 


gnstable and tangible. Taste is therefore a special form of 
the tactual or haptic sense. It is not perceived through 
the medium of a foreign body but through an anatomical 
medium, in which respect it differs from the senses of sight, 
hearing, and smelL The latter are marked by actio in 
didana, while taste and touch operate by immediate 
contact. This immediate contact is not the direct contact 
of the sense-object with the sense-organ, which is found in 
no sense, but the direct contact of the sense-object with our 
physical organism as a transmitting medium. Touch is 
more exquisitely developed in man than in any other 
creature, and taste, as a kind of touch, shares in this per- 
fection. The gustable or flavour is the sapid-moist 
Gustable juices are developed in water or in a moist 

There is a great variety of opinions as to how these 
qualities originate in water.^ Water is not to be regarded 
as panchymic in the sense of containing originally the 
germs of all flavours, as was held by Elmpedocles, but as 
primarily neutral and only potentially chargeable with 
flavour. It may be so charged by the processes of nature 
or by artificial meana* Flavours in the moist are especially 
developed under the influence of heat. The primary 
elements taken alone are tasteless;' flavour arises only 
in their combinations, and it is only in forms of combina- 
tion that the elements are fit for food.* Flavour and 
the nutritive are closely connected, sweet being the most 

1 De sensu^ 441a Iff. ^ De aenau, 4416 12ff. 

' De aensu, 44da 8 ff.; MeUor. 3586 18. 
* De aensu, 4416 24ff.; De an. 4d46 19ff. 


important flavour in growth.^ The basal flavours are sweet 
and bitter,* from which are derived the other flavours. 
The number of flavours, like the number of colours, is 
seven : sweet, bitter, salt, harsh, pungent, astringent, acid.* 
c. The Medium of Taste, — As pointed out above, the 
medium of taste is not outside the body, yet taste operates 
through a medium.* We can, indeed, taste in water, but 
water in this case is not the medium ; it is charged with a 
gustable substance and so becomes the object, not the 
medium, of taste.^ The medium of taste is the tongue.® 

5. Toncli. 

Touch and taste are the most fundamental and therefore- 
the most universal of the senses, because they are necessary 
for the maintenance of animal life. No animal can exist 
without touch, and only animals can possess it. As it is 
necessary to animal life, any stimulus sufficiently excessive 
to destroy it, destroys not only the organ, as in the other 
senses, but life itself. The other three senses, especially 
sight and hearing, minister to higher well-being and fur- 
nish materials for intellectual life. Touch and taste are 
of primary importance for the maintenance of physical 
well-being.^ Although the sense of sight is the most im- 
portant of our senses for higher well-being, because of 
the great number and variety of sensations with which 
it furnishes us,® yet that man is the most highly endowed 

> De 8en9U, 442a 2 ff. * />e an. 4226 11 ; De aensu, 4426 16 ff. 

* Cf. translation, p. 87, note 2. * De an. 435a 16, 422a 9. 

» De an. 422a 12. « De an. 423a 16, 4236 17, 26. 

7 De ftensu, 4366 10 ff. ; De an. 4146 2 ff. 

* Metaph. 080a 21 ; De atnsu, 437 a 5ff. 


creature is shown more by his touch than by his sight, in > 
which latter many of the lower creatures surpass him. 
Further, men of finest tactual sensibility are the best 
endowed intellectually.^ 

a. The Organ of Touch, — As in the case of taste it is not 
made clear what the organ is, so it is not made clear 
in the case of touch. The organ is described merely 
as something intra-corporeal. i.e. it is not the superficies 
of the body. This may refer to the central organ as 
some suppose,^ or, as I think more probable, to some unde- 
fined and unknown peripheral organ within the flesh.* 

6. The Object of Tov/ih, — The object of touch is the 
tangible (aTTov).* Aristotle's expression contains the 
same tautology. Tactual distinctions are such as charac- 
terize the body as body. They include warm and cold, dry 
and moist, hard and soft.* The objects of touch do not fall 
under a single category. The objects of sight fall under 
the category of colour; those of hearing under the category 
of sound ; but the objects of touch are not reducible to this 

c. The Mediv/m of Touch, — As it is the function of touch 
to apprehend the qualities of body as body, so it is a cor- 
poreal medium that transmits these qualities, viz. the flesh. 
This sense gets its name from contact, which is possible 
only between bodies. The body in general is the medium 
of touch, and the tongue is the medium both of touch 
and taste. 

1 De an, 421a \5fL >Cf. ZeUer's Aristotle, Eng. tr., voL it, p. 66. 

*Dean, 422622. *I>e cm, 4346 12; De gener, et corrvp, 3296 8. 

* De an, 4236 28ff. ^De gener, ei carrup, 330a 26; Dean, 4226 32. 




From the foregoing it will be seen that Aristotle 
/ hampered as he was by the lack of scientific research in 
physiology and physics amongst his contemporaries, struck 
4x)ldly out into the Urrra incognita of psychophysics as a 
discoverer. His is not only the first attempt to create a 
psychology in any approximately scientific spirit, but it is 
the first attempt to formulate a psychology at all. 


The CJommon or Central Sense. 

Aristotle's conception of a 'common sense' (koivov 
alrrOfrrripiov)^ has no logical or historical connection with 
the Scottish philosophy of common sense. Sir William 
Hamilton, in his elaborate note appended to the works of 
Reid),* gives four meanings in which the term ' common 
sense' has been employed in ancient and modem times: 
1. It was employed by Aristotle and the Peripatetics to 
signify sense proper, and denoted that faculty by which 
the various reports of the individual senses are reduced to 
the unity of a common apperception. 2. It has been 
applied not to sense proper, but to those cognitions and con- 
victions which we are supposed to receive from nature and 
which all men possess in common, whereby we test the 
truth of knowledge and the morality of acts. This is 
the meaning in which it is employed in the Scottish philo- 
sophy. McCosh called it the Intuitive Philosophy, i,e, the 

^De an, 425a 14 ff. ; Dt somno, 455a 21 ; De long, et brev. vU, 467628, 
469a 12. 

' Reid's Works, edited by Hamilton, vol. ii., pp. 751 S, 


philosophy which regards the common intuitions of the 
mind as the criteria of truth. 

Dugald Stewart objected to the term ' common sense ' on 
the ground of its ambiguity, and preferred to call these 
common convictions ''the fundamental laws of human 
belie!" Common sense, he asserts, is nearly synonymous 
with mother-wit, and good sense is only a more than 
ordinary share of common sense. These primary or intui- 
tive truths are what Arist.otlft calls ultimate principles 
'{apxai), but not principles of common sense. He says in 
the Nicorruichean Ethics : ^ " What all men believe, that we 
affirm to be ; and he who rejects this belief will advance 
nothing that is more convincing," which is the equivalent of 
the dictum : quod semper, quod ubiqv^, quod ah omnibus. 
These universal beliefs, which Aristotle regards as the 
fundamental principles of human knowledge, are akin to 
the ' fundamental laws ' of Stewart. The doctrine of the 
sensus communis^ however, is quite distinct from this. 

3. Common sense, when used with an emphasis on the 
adjective or substantive, indicates that kind of intelligence, 
the lack of which causes one to be accounted mad or foolish. 

4. It denotes an acquired perception of the duties and pro- 
prieties expected from each member of society ; a sense of 
public spirit, a feeling of obligation towards the commonweal 
The last three meanings are all metaphorical, and do not 
refer to sense proper, but to certain intuitions which, like 
sensation, are characterized by immediacy, originality, and 
presumed trustworthiness. Thus we speak metaphorically 
of a ' moral sense,' a ' logical sense,' or an ' aesthetic sense.' 

^Eth.Hic. 1173a 1. 


Aristotle employs 'common sense' to signify a specific 
aspect in the psychological process of sense-perception. 
The act of sense-perception is not completed in the peri- 
pheral sense-organs, but only in the central sense.^ There 
are, as enumerated in the previous chapter, five peripheral 
organs of sense : the eye, ear, tongue and throat, nose, skin 
and flesh. These are stimulated by objects in the outside 
world, which by contact with the organ work some change 
{aWoiaxrii) in it. The contact is efiected through a medium 
which transmits a stimulus from the sense-object to the 
perceiving organ, and the change which the stimulus works 
in the peripheral organ is further transmitted by the blood 
or sense-duct to the aevsorium (central organ). In every 
sensation three factors are to be taken into account : (1) the 
organ, (2) the object or thing sensed, (3) the medium of 
transmission. In the case of vision, as explained in chap, 
rv., these factors are the eye, the thing seen, and the 
diaphanous or translucent medium, whether the latter be 
Kquid or atmospheric. 

Every sensation presupposes these three elements: 
organ, object, and medium. To each of the individual 
senses belongs the function of apprehending a particular 
quality (JSiov alrrQirrov)?^ In vision, only colour is sensed ; 
in hearing, only soimd ; in smell, odour ; in taste, flavour 
and in touch, the qualities of body as body (hardness, etc.). 
These are all sensation-qualities, but they are not percepts. 
By means of sight,, we have the sensation of green, but 
do not perceive an olive. An olive is a percept ; green is a 
sensation. An olive is made up of several ideas, of hard- 

^Dt an, 4266 lOff. ; Dt aomno, 455a lOtL '2>e an. 418a lOff. 


nesB, taste, colour, form, magnitude, etc., and these are 
unified in a particular thing, and they constitute it a single 
concrete object. The peripheral organs of touch, taste, and 
sight furnish us with several ideas or qualities belonging to 
a concrete thing ; but it is only by the unifying function 
of the central or common sense that these various qualities 
are brought together for knowledge and seen to inhere in 
a single object; in other words, it is only then that a 
percept is formed. The function of sensation, therefore, 
belongs to the peripheral or external senses in so far as 
they mediate the qualities of an object to the aenam^ium or 
common sense. Perc&ption} then, is one of the functions 
of the central sense. 

Again, it is by means of the central sense that we 
recognize particular sensations as belonging to ourselves, 
and can hold them up before our minds as something known 
to us. We know that we see. In other words, we are 
conscious of a sensation. Gonaciousneaa? then, is a second 
function of the common sense. Locke made a distinction 
between what he called the external and the internal senses. 
The external sense gives us ideas of colour, sound, and other 
properties of body. The internal sense gives us ideas of 
thought, reasoning, memory, and the other operations of 
our own minds, and is another name for consciousness. 
This function, so far as it is limited to the consciousness of 
sensations and their meaning for perceptual knowledge, is 
ascribed by Aristotle to the common sense. 

Again, there are in addition to the particular sense- 
qualities (f&a altrdrp-a), such as odour, sound, colour, etc, 

^2>6Mfu«,449ad£ 'Z)e an. 4256 12 £; Z>e mywu, 456a 15ff. 


oertain^roperties attaching to things which Aristotle calls 
"^ common sensibles ' (KOiva aia-Onra).^ These are rest, motion, 
number, shape, and magnitude. They are called ' common " 
because their apprehension does not belong directly to any 
particular sense (although they are perceived indirectly by 
each), and because they are cognized directly by the common 
sense. They diflFer from primary or simple sensibles in 
having no specific sense-organ. This is a third function of 
the aensorium commune. Again, the individual senses 
furnish us with colour, sound, etc., but it is not their function 
to discriminate, e.g., between sweet and white, or to differen- 
tiate degrees of bitter. This is a function oijvdgment^ and 
it is ascribed by Aristotle to the common sense. The dis- 
crimination between true and false, between real and 
unreal in our perceptions is made not by the peripheral 
senses, but by the central sense. The sensation, because it 
is only a fact and as a sense-process pronounces no judg- 
ment, is always true,' but when the sensation is predicated 
of something and a judgment is expressed, error is possible. 
It is the internal or central sense that performs this office 
of judgment in the sphere of perceptual knowledge, and it 
is, therefore, to the central sense alone that, strictly speak- 
ing, truth and falsehood in this sphere can be ascribed. 

Further, sleep,* imagination,*^ memory,^ and dreams,^ in 
so far as they signify the interruption of consciousness or 
the continued life and movement of residual sense-percep- 

^ De an, 418a 17, 425a 16 ; Dt mem, 450a 10. Cf. translation, p. 96, 
note 2. 
^De an, 4266 14 ff. ' De an, 4276 11, 428a 12. 

* Dt aamno, 454a 23, 456a 1. ^ De imom. 4606 17. 

< De mem, 451a 17. "^ De inaom, 4586 1 ff. 


tions, are functions of the sensorium. In summary, these 
various functions of the central or common sense are as 
follows : 1. The unification of the primary sensibles, or the 
complete act of sense-perception ; 2. Consciousness ; 3. The 
suspension of consciousness, or sleep ; 4. The cognition of 
the 'common sensibles/ magnitude, number, etc; 5. Judg- 
ment, in so far as judgment applies to the comparison, 
contrast, and discrimination of the deliverances of sense; 
6. Imagination, or residual sense-images ; 7. Memory (in- 
cluding reminiscence), or the voluntary and involuntary 
reproduction of sensations; while lastly, 8. its content is the 
potentiality of reason. 

As the peripheral senses have an object, a medium, and \ 
an organ, so also has the central sense. The objects are they 
'common sensibles' and the several particular sensations 
which are unified by the central sense into the perception 
of a single concrete thing ; the medium is the blood and the 
particular sense-organs ; and its own organ is the heart.^ 

^De Juvent, 467628 ff., 469a 11. Aristotle's reasons for rejecting the 
brain as the sensory centre may be summarized as follows : 1. The brain 
of a living animal appears to be insensible to touch {Hint, anim, 520616). 
2. Aristotle was unable to discover any brain in the invertebrates, except- 
ing the Cephalopods. The ganglia in other invertebrates, owing to his 
lack of instruments, escaped his notice. 3. The peripheral organs (eye, ear, 
and nose) are not, strictly speaking, connected with the brain, but only 
with the vascular membrane surrounding it. 4. The sense-ducts are con- 
nected with the heart, from which radiates the entire vascular system. 
5. The heart is the primum vivens, vltimum moriens {De part. anim. 
666a 20, 667a 20 ff. ; DejuverU. 468628) in animal life, and as sensibility 
is the most fundamental animal characteristic, so the heart would appear 
to be the most fundamental organ of this characteristic. 6. With loss of 
blood sensibility is lessened. 7. The heart's action is plainly affected by 
pleasure and pain. 8. Its central, acropolis-like position indicates that 
nature's economy intended the heart to be the organ of government. 



Imagination and Memory.^ 

The process of knowing, according to Aristotle, develops in 
three diflFerent stages : 1. The primary stage or simplest 
form of knowing is sensation (aTcrfli/o-iO ; 2. The second 
stage is imagination (ipavraa-la), or the power of using 
images of absent objects; 3. The third stage is rational 
thought (vovgy Although imagination differs from sen- 
sation and conceptual thought, it is not possible without 
sensation ; and thought, in turn, is not possible without 
imagination. Imagination is the persistence of a sense- 
impression after the removal of the sense-stimulus, described 
by Hobbes as "decaying sense," ^ and by Aristotle as a 
weaker* or less clear sense. 

Imagination mediates between sensation and thought. 
Sensation furnishes the mind with a body of impressions 
and copies of the external world, — ^the raw material which 
imagination and thought employ.^ Imagination is a store- 
house, as it were, of copies of sense-objects, which persist 
in the mind as images after the seen or heard objects have 
been removed. I no longer hear, e.g,, the song that once 
stirred my sense, yet it sings and repeats itself in the 
auditory imagery of my mind. I no longer see the player 
distraught with the woes of Oedipus, yet the picture of 

^See translation, pp. 110 ff. 

'"Imagination therefore is nothing but decaying sense," Hobbee' 
Leviathan, Part I., ch. 2, p. 7. Oxford, 1881. 

' Rhet, 1370a 28. 

* Aristotle's distinctions between imagination and sensation are more 
minutely given in note 1, translation, p. 110. 


his tragic face remains in my life of visual imagination. In 
this meaning, imagination is the power to hold the im- 
pression of sense after the sense-object has gone. Sensation 
refers to a present impression; imagination refers to an 
impression of something that is no longer before us. 
Imagination is necessary, therefore, to the life of thought / 
and memory, for without it mind would be only the ever- 
shifting scene of kaleidoscopic sense-impressions which, 
once gone, could never be revived. Imagination partakes 
of the nature of both thought and sensation ; like thought, 
it is a subjective, internal activity ; and like sensation, it is 
the passive receiver of images and forms from the external 

The word fpavraa-la is used by Aristotle to mean both 
the faculty of imagination and the product of imagination. 
For the latter meaning, however, he ordinarily employs 
the word phantasm {<f>avTacrfxa), There are three more 
or less distinct senses in which Aristotle makes use 
of the term phantasm: 1. Appearance; 2. Phantasm or 
false appearance; 3. An internal mental picture of an 
absent sense-object. It is in the last meaning that the 
term is usually employed in his psychological treatises. 
The word (pavraa-la is akin to <j>ao^ ('light'), and 
<f}avTd^€(rdai ('to appear'); and there is in the word an 
implied distinction between the phantasm and the real; 
it is appearance versus reality. Yet while the image is not 
the real thing but only the real thing's form, it may be 
a true copy of the real, and, as such, it is as true as sensa- 
tion. The two prominent elements expressed in the word, 
looked at etymologically, are form and light, without 


which the sensible world is not revealed to us. As the eye 
reveals to us an external world of jEorm and light, so 
phantasy reveals to us an inner world of forms, colour, 
perspective, and light, — an inner world corresponding in 
its imagery to the world of lighted space. 

The psychophysical process by which imagination is 
produced is conceived by Aristotle as follows : Sensation is 
due to a movement set up in the sense-organ by a present 
stimulus This movement has the power to persist after 
the stimulus has been removed. Just as one throws a 
pebble into the water and sets up a circular movement 
therein, and this moving circle creates a second by its 
energy, even after the pebble has disappeared, and the 
second circle in turn communicates its movement to a third, 
growing fainter the while, so a sense-stimulus sets up a 
movement in the sense-organ, which in turn communicates 
its movement to the blood, and the blood, under favourable 
circumstances, conveys it to the heart, which is the organ 
of consciousness and of the higher activities of the mind. 
By favourable circumstances Aristotle means cases where 
the movement is not inhibited or interfered with by 
counter-movements of sensation, and where the sensation 
is strong enough to persist. In the midst of the cross- 
currents of our motley life of sensation, the movements set 
up by given stimuli are constantly crossed and impeded by 
other movements, and there arises amongst them, as it were, 
a struggle for existence, to employ a much used formula of 
modem biology.^ Those movements which at the moment 
are strongest, reach the heart and become phantasms or 

1 Dt tMorn, 461a Iff.; De an. 4286 10 ff. 


conscious imagea Similarly also to the fainter expression 
of the communicated movement in the illustration drawn 
from the pebble,^ the communicated movement in the 
phantasm is fainter than that in the original sensation. 

In a passage in the Rhetoric already referred to, 
Aristotle describes a phantasm as a "weak sensation/' 
whidi is very like the view of Hobbes, who says: ''All 
fancies are motions within us, reliques of those made in 
the sense." ^ These movements of the imagination are, as 
one might expect, especially characteristic of sleep, during 
which the sense-activity is suppressed. Dream-images are 
not always copies of the real world, but often merely a mass 
of confused, distorted forms having no apparent relation to 
actual things. Imagination, therefore, has two forms : ^ 
(1) That of revived or residual sense-perceptions, i,e. copies 
or images of the real world, in which the imagination is 
passive or receptive ; (2) That of reconstructed or created 
images, in which the imagination is active and productive. 
The one form of imagination is called by Aristotle fj^avraa-la 
cua-Ofp-ucii, the perceptual or reproductive imagination, and ^ 
the other form if>avTa(ria Xoyiarixriy the constructive or pro- ^ 
ductive imagination.* The latter belongs only to man, the 

^ De tnaom. 461a 20 ff. and note 1, translation, p. 242. 

* LevieUhan, p. 12 (Part I., ch. iii). Cf. Freadenthal, Ueber den Begriff 
de$ Wortes ^ourrcurla bet Aristoteles, p. 24. 

' In modem psychology imagination and thought are less differentiated 
than in Aristotle's writings, where imagination is always either the reproduc- 
tion of sense-elements or their reconstruction into new images, without loss 
of their sensuous or picture character. Of constructive imagination Titchener 
says : " It is a ' thinking ' or judging not in words but in reproductive ideas. 
Psychologically, then, there is no difference between the 'imagination' 
of the poet and the 'thought' of the inventor" {Outline of Peychclogy, 
p. 297). 



former to the brute creation as well as to man. Further, 
the imagery accompanying general notions and conoep- 
tual thought is a creation of the productive imagination. 
The latter form of imagination is due to a free initiative 
power in the central organ, which may take the character 
of a logical construction of the elements of sense-imagery 
into a coherent complex, such as is exhibited in a creation 
of Uterary or plastic art; or it may take the form of 
arbitrary, incoherent, confused image-masses, as exhibited 
in sleep, in the delirium of fever, or in the excitement of 
vehement desire or violent passion. Such distortions and 
malformations, corresponding to no real things, are due 
mainly to physiological causes, especially to excessive heat 
and disordered movements in the blood. They occur 
mostly in sleep, because the activities of thought and 
sensation, which act as regulators of imagination by day, 
are suppressed in sleep, and, consequently, the activities of 
imagery have then complete control of the central organ. 
These phantasies, uncontrolled by waking consciousness, 
resemble the imagery of clouds, which, as Aristotle says,^ 
at one moment represent a centaur, at another a man, and 
are constantly shifting in their forms. Melancholy has 
great influence in the production of pictures of phantasy, 
because it generates excessive heat in the central organ ; so 
also have such pathological conditions as are found in 
ecstasy and madness, observable in the case of sibyls and 
religious maniacs, in whose minds the pictures of fancy are 
regarded as real objects. In these cases right judgment, 

^Dt inaom, 460612, 4616 20; Metaph. 1024622; Proh. 9953a 10 ff., 
9576 10 ff. 


which normally assists in the regulation of the image- 
making function, is inhibited. Imagination, then, is for 
Aristotle both an image-receiving and an image-producing 
power.^ As an image-receiving or image-holding power, it 
is the source of memory and recollection. This is the 
reproductive function of imagination. A memory or 
memory-image differs from a phantasm in two particulars : 
(1) memory regards the phantasm as a copy of something,^ 
while imagination regards it simply as a picture; (2) 
memory regards the thing, of which the phantasm is ap 
copy, as having been seen or known by us. It is recog- 
nized as part of a past experience. 

The deliberate and conscious calling up of this copy~y 
is recollection {avaiJiVTi(ri9). Recollection depends on the 
original coherence of the movements or elements in experi- 

^ That Aristotle employs imagination in these two senses is, I think, 
demonstrable. The terms above cited, ^ovrcurfa alaOrfTtiHj and ^yraaia 
}i€ytffTiKi/f {De an. 4335 29), are thus most consistently explained. Further, 
in the aims of art and the ends of conduct Aristotle employs imagination 
in the constructive or productive sense (De poet. 1455a 22 ff.; Mh. Nie. 
11386 20 ff.), and he sharply distinguishes between the sense-imagination of 
the lower animals and the rational employment made of it by man (Z>e an, 
434a 6, 429a 1 ff. Cf . Frohschammer, Ueher die Principien der aristoteliachen 
PkUowphU, pp. 52 ff. ; and Teichmilller, Aristoteliache Forschimgen^ 
Vol. II., pp. 149 ff.). Again, it is possible to call before the mind an 
imaginary object, a new and more or less arbitrary construction, which is 
not possible in reproductive imagination or in discursive thought controlled 
by rigid laws of procedure (De an. 4276 15 ff.). Butcher, although he 
denies that Aristotle employed the term in a productive sense, yet in his 
account of phantasy implies (correctly, I think) that Aristotle did use the 
term in this meaning {Aristotle* s Theory of Poetry and Fine Art, pp. 126 ff. 
and Preface, p. viii. Cf. also Freudenthal, op. cit., pp. 31, 45). It is not 
to be supposed, of course, that Aristotle thinks of two imaginations, but 
merely of two functions of this psychological power — the one concerned 
with the reproduction of sense-elements, and the other with their logistic 
or rational reconstmotion into new forms. 


ence. By virtue of this original coherence one image is 
called up by another formerly connected with it. The laws 
of association in memory^ are described by Aristotle as 
(1) similarity, (2) contrast, (3) contiguity.* 

Productive or active imagination, on the other hand, 
creates images that do not correspond with past experiences 
or sensations, but which have only an ideal or subjective 
existence. These images are the phantasies of dream-life, 
of delirium, of art-creation, etc. It is to the imagination 
that art appeals. The image-making power is the sub- 
jective source of art imitation (jiifAffa-ii)- It is the function 
of imagination to clothe the idea in a picture or figured 
space and thus to mediate between the outward work of 
art and the internal idea. Art, m Aristotle's opinion, is 
essentially mimetic Imitation in art is, in the first place, 
an imitation of a picture in the phantasy. Measured 
alongside the work of art, the mental picture or phantasy 
is an abstraction. The work of art is the concrete ideal, 
and here phantasy is active and creative. The mental 
image itself, however, is either a mimetic picture of the 
sensible real or it is a purified picture of the sensible 
real When art is not merely mechanically reproductive 
or crudely mimetic, but is the purified or cathartic picture 
of the real, then (Aristotle says) poetry is more philoso- 
phical and more serious than history.* History is par- 
ticular ; poetry and art are universal, idealistic 

^ Aristotle says that experience, which is akin to science and art, is 
derived from 'much memory* {AnaL post, I00a5 ; Metaph, 9806 29). Cf. 
Hobbes' LtviaAkan (ch. ii., Part L), p. 7 : "Much memory, or memory of 
many things, is caUed experience." 

> 2)e mem. 4516 10 ff. ^DepoeL 14516 6£ 


The relation between phantasy and artistic genius is 
unfortunately scarcely more than touched upon by Aris- 
totle. Imagination is the normative and directing power 
in art, because it is imagination that places before the 
artist the end he wishes to attain, and this end 'is given 
in the form of a mental picture or image. The art-object 
exists in phantasy prior to its existence in reality. The 
creations of art are the projections of internal phantasms 
into the various forms of art-expression,— into the form 
of fixed and arrested matter (sculpture and architecture),^ 
or into the form of fluent, rhythmic verbal sjrmbols 
(poetry), or coloured superficies (painting), or melodious 
sequence of soimds (music). In every instance art is 
concerned with appearances (^vrao-^iaTa), and is, there- 
fore, always sensuous. It is clothed exclusively in imagery 
drawn from the sense-world, even the rhythm of poetry 
being an imitation of aesthetic movement in a world 
of sensible motion. 

The final function of imagination, in Aristotle's account, 
is to supply the schematic form in which the higher 
activities of conceptual thought are clothed. The reason 
needs general images for the schematism of general 
notions, and such schemata are supplied to vou^ by the 
productive imagination. Furthermore, imagination medi- 
ates the sense-world to the reason, and thought interprets 
the imaged world of sense in the forms of science and 

^ Architecture is not incladed amongst the fine arts by Aristotle, becanse 
it serves practical ends and its primary purpose is not to minister to the 
aesthetic emotions, and farther because of its non-imitative character. Cf. 
Bntoher, ArisUMa Theory of Poetry and Fine AH, pp. 146 ff. 



Practical Reason and Will. 

The practical reason differs in its function from the 
theoretic reason. These are not two reasons, but one 
reason operative in two distinct fields, viz. in the field of 
knowledge and in the field of morality; and as the subject- 
matter and results in the two cases differ, so the two 
functions have received different namea The function of 
the theoretic reason is to discriminate between the true 
and the false; the fimction of the practical reason is to 
discriminate between the good and the bad.^ The former 
knows ; the latter judges, weighs, evaluates, advises, and 
determinea The practical reason is concerned with de- 
liberation and conduct, with knowledge as applied to 
action ; the theoretic reason is concerned with knowledge as 
such. The theoretical reason gives no oommand& The 
practical reason operates in the form of a practical syl- 
logism, whose conclusion is epitactic or imperative. 

Aristotle describes this syllogism as follows: All de- 
liberate action is resolvable into a major and minor 
premiss, from which the given action logically issues. 
The major premiss is a general conception or moral 
maxim ; the minor premiss is a particular instance ; and 
the conclusion is an action involved in subsuming the 
particular instance under the general conception or law. 
The conclusion is not an abstraction, as in the case of a 

^De an. 4316 10, 433a 14, 434a 16 ; ^^. nie. 1144a 31 ff., 1147a 1 ff.; De 
motu anim, 701a 7 fL 


theoretical syllogism, but consists in an action and is 
jussive, e,g} 

Major pi-emiss : All men should take exercise ; 

Minor premiss : I am a man ; 

Conclusion : I should take exercise ; 

Light meats are wholesome, 

This is a light meat, 

.*. It is wholesome. 
Our English phrase 'acting on principle' is, as Grant 
pointed out, the equivalent of Aristotle's practical syl- 
logism.* The practical syllogism operates in the sphere 
of conduct, of choice and the variable * (ra evSexoimcva aX\m 
€xciv)f not in the sphere of necessary truth as is the case 
with the speculative reason, whose aim is demonstrable 
truth, whereas the aim of the practical reason is the good, 
the prudent, the desirable. The content of the conclusion 
as knowledge is the essential matter for the former; the 
content of the conclusion as motive is the essential matter 
for the latter. The main business of the former is with 
the imderstanding, of the latter, with the will ; the prin- 
ciple of * sufficient reason ' is related to the understanding 
as the principle of * final cause * or motive is related to the 
will.* In the practical syllogism obligation is vested in 
the conclusion, and the particular or minor premiss is more 
cogent than the major, i,e, it is not the general law, but the 

1 De motu anim. 701a 27 ; Eth nic. 11416 18 ff. 

*The Ethics of ArvUoUe, edited by Sir A. Grant, Srd ed., London 
1874, Vol. I., p. 269. 
^Eth, nic. n40ad2fL, 1141a 1 ff. 

* Cf. Grant, op. cit,, p. 263. AIbo De an. 432a 10 ff., translation p. 132. 



application of the general law to a particular person, that 
stimulates to action.^ 

The virtue characteristic of the practical reason is 
prudence or practical insight {<f>p6vri(rii)' "Prudence is 
neither a science nor an art ; it cannot be a science because 
the sphere of action is that which is variable ; it cannot be 
an art,* for production is generically different from action;"* 
and although Aristotle rejects the Socratic doctrine that 
x^"** virtue is knowledge (the sphere of moral life is pleasure 
and pain, rather than knowledge),* he goes on to say that 
the " presence of the single virtue of prudence implies the 
presence of all the moral virtues/' ^ Prudence, however, is 
not itself the whole of moral virtue : " moral virtue makes 
us desire the end, while prudence makes us adopt the right 
me€uis to the end." ® Although men act on general principles 
and laws, they do not perform general acts ; all acts are 
particular; and so Aristotle, in describing the practical 
reason and its characteristic moral quality of prudence, 
further differentiates it from the theoretic reason by saying 
it is concerned immediately with particulars (aia-Offa-i^, 
eaxoTOVt irpatcrov ayadov, to kgO* eKacrrov)? 

The jussive character of its conclusion is, indeed, derived 

^ De an, 434a 17. 

'Human activities are classified by Aristotle into three main groups : (1) 
knowledge, (2) action, (3) production (art). To these three groups of 
activities he assigns the foUowing corresponding forms of science : (1) 
theoretic, (2) practical, (3) poetic. Cf. MetapK 1025620 ff. 

^Eth. nic, 114061 ff. 

*Eth, nic. 110469. 

^Eth, nic. 1145a 1 Peters' translation (4th ed., London, 1891), Bk. 
VI., 13, 6. 

•Eth. nic. 1146a 6 (Bk. VI., 13, 7). 

''Eth. nic. 1141616, 28, 1142a 22, 1142a 25-30. 


from the major premiss, but only by applying the major 
premiss to a particular instance. The empirical knowledge 
of particular facts is more immediately important. " Prud- 
ence ^ does not deal in general propositions only, but implies ^% 
knowledge of particular facts also ; for it issues in action, 
and the field of action is the field of particulars. This is 
why some men who lack scientific knowledge, especially 
men of wide experience, are more efficient in practice than 
others that have such knowledge. Prudence is concerned 
with practice and needs both general truths and particular 
facts, but more especially the latter." * It is the particular 
or minor premiss that is most cogent in stimulating to 
action. The minor premiss, however, is immediately per- 
ceived and often obvious, and the practical syllogism then 
has the form of enthymeme. 

The epitactic quality of the practical reason is not think- 
able apart from the virtue of the will. It can legislate, 
but not execute. Volition is not vested in it, although no 
moral volition is possible without it. However, as a 
legislative power it guides the will by enlightening it. 

^ Walter identifies practical reason and prudence, and regards the 
doctrine of a voOs TpatcriKbs as a late interpretation of Aristotle, due to 
an incorrect translation of Albertus Magnus. Walter's distinctions, 
although very acute, seem to me not only unprofitable refinements, but 
of questionable hermeneutic soundness. The fact that the process here 
referred to is described by Aristotle as syllogistic and issuing in conduct 
{De an. 433a 1-16), and the frequent reference to practical reason as a 
distinct psychological power [TpaicTiKbs ¥oui, De an. 433a 16, Eth, nic. 
1142a 25-30; duivMa TpaxriK-fi, De an. 4336 18, Pol. 13256 18 ; X&yot wpaxrucds, 
Pol. 1.333a 25), seem to show that Aristotle regarded this not only as different 
from the theoretic function or reason, but also as different from ^p6in!i<r^t 
(prudence) as a moral quality. Cf. Walter, Die Lehre von der praktiachen 
Vemunfiy Jena, 1894, pp. 15 ff 

^Ethnic 11416 15 ff. 



By will Aristotle understands any effort towards the good. 
The lowest form of will is impulse; its highest form is 
rational desire. 

Aristotle, like Plato, developed his ethical doctrines in 
the closest connection with his psychological theories. His 
conception of the moral will and its function is determined 
largely by his theory of the practical reason. In his 
, analysis of the elements of consciousness, he finds only what 
' we should call ideational and affective elements. There 
_ is no reference to any third conative element. The two 
component elements in the ethical will are practical reason 
and desire (ejriOviJua, ope^ii)} Desire, as Aristotle employs it, 
is not a purely pathic or affective element. Feeling as such 
(theoretically) is completely passive, — mere enjoyment of 
the pleasant or mere suffering of the painful. Aristotle, 
V however, describes desire as an effort towards the attain- 
ment of the pleasant, i.e. he includes in it an activity or a 
conative element. It is feeling with an added quality of 
impulse (Trieb). More specifically and in detail the elements 
contained in it are: (1) An idea or presentative element. 
There can be no desire without cognition or imagination 
{opcKTiKov Se ouK av€v <f>avTaa'iai)-^ An animal cannot desire 
that of which it has no image. (2) An element of feeling. 
In every desire or aversion there is an element of pleasure 
or pain.* (3) An element of effort or activity.* Desire 
involves pursuit or avoidance, and in it is given a spring 

i De an. 43266 ff., 433a2 ff., 41465, 433a 1—4336 30, 431a 12 ; De aamno, 
454631 ; Eth. nic. 1094a21, 1139a 22, lllla32 ff. 
>i)e an. 4336 28. 

'Z)e an. 413623, 434a3; Eth. nic. 1175627. 
«i>e an. 433a 9-21 ; Mh. nie. 11116 17, 1139a 22. 


of action. The object of desire is the motive in conduct.^ 
The pleasure that is felt or anticipated is the object of effort 
and the initiator of movement, and it is through desire 
that the practical reason operates indirectly on actions. 
" Mere reasoning never sets anything in motion, but only 
reasoning about means to an end or practical reasoning/' ' 
ix. reasoning which guides or modifies the desires. 

This deliberative process of the practical reason, issuing y ^ 
in an imperative conclusion and combined with desire, con- 
stitutes for Aristotle the moral will. The reason alone does 7 
not produce action, and the desire alone is non-rational and 
non-moraL Aristotle, therefore, defines the moral will 7 
(irpoalpea-ig)^ as desire penetrated by reason, or reason 
stimulated by desire (ope^i^ Siavotprucii, voO^ opeKTuco^).^ 
The practical reason contains a jussive force and rightness, 
while desire supplies an active, appetitive quality. The 
moral will, therefore, is a complex of reason and desire, 
and is supposed by Aristotle to function under the follow- 
ing modes : (1) deliberate choice ; (2) purpose ; (3) freedom ; 
(4) fixed habit. By means of particular acts issuing from 
free and deliberate choice is generated the individual's 
moral character, which Aristotle describes as fixed habit 
(S^ii) * or the persistent will. v 

Aristotle maintains the freedom of the will, and says it 
is in our power to be "worthy or worthless."® This, he 
argues, is attested by our own consciousness of power to 

' De an, 4336 11. > Eth, nie, 1 \39a 36. 

*Eeh, nic. 1106a3, 1113a 11 ff., I139a31, 33, 113964; De mot. anim. 
700623. *Eth. nic, 113964, 1102630. 

'^CaUg. 8628, 9a6; EtKnU. 1106a 22, 1105625, 1157631. 
•Eth. nic, 1113614. 


do or to refrain, by the common testimony of men, by the 
rewards and punishments of rulers, and by the general 
employment of praise and blame. Particular acts are 
always in our power, and we are responsible for them, — 
we may not contend that because they are determined by 
temperament or character, they are not free and we are 
not responsible.^ "We are masters of our acts from 
beginning to end, when we know the particular circum- 
stances ; but we are masters of the beginnings only of our 
habits or characters, while their growth by gi'adual steps is 
imperceptible, like the growth of disease. Inasmuch, 
however, as it lay with us to employ or not to employ our 
faculties in this way, the resulting characters are on that 
account voluntary.'* ^ In a certain sense we are creators of 
our own determinism, paradoxical as this may sound. 
Aristotle says in the Topics that man is determined in 
the sense that " a man's destiny is his own soul," * although 
its character is his own voluntary creation. It is true 
that by voluntary particular acts a man becomes volun- 
tarily just or unjust, "but it does not follow that, if he 
wishes it, he can cease to be unjust and be just, any more 
than he who is sick can, if he wishes it, be whole. And it 
may be that he is voluntarily sick, through living incontin- 
ently and disobeying the doctor. At one time, then, he 
had the option not to be sick, but he no longer has it, now 
that he has thrown away his health. When you have 

^Eth. nic. 111365 ff. (Bk. lU., ch. 5). 

^Elh, flic. 1114626 ff. (Peters' tranalation, 4th ed., London, 1891, 
Bk. lU., ch. 6, end). 
' Top. 112a 38, ra&niv (bc. ^vxV) 7^ ixd^rov etvcu dcUfiova. 


thrown a stone, it is no longer in your power to call it 
back." 1 

In the foregoing I have had regard only to the moral 
will. In a general sense, however, — perhaps akin to 
Schopenhauer's conception, — Aristotle employs the term 
eve/aye/a (all organic effort) as will. This form of will or i 
activity is, in his teleological view of the world, impulse to 
the good or a striving towards self-realization, whether in 
plant or animal. It manifests itself in psychical life in 
such various forms as nutrition, locomotion, sensation, and 
rational activity. The whole of psychical or organic life, 
therefore, is regarded from the standpoint of will or 
activity tending designedly towards the realization of a 
given potentiality. But will in the moral sense, the 
voluntas intellectiva of Thomas Aquinas and the will of 
modem ethics, is rationalized desire or feeling acting under 
forms imposed by reason. 


Creative Reason.^ 

Aristotle's account of the theoretical activity of reason 
is very meagre, — wholly inadequate for any reconstruc- 
tion that is not speculative and tentative. Even the 
learned commentator TheAiistius says regarding the 
doctrine of the active reason : " The philosopher himself 
{i.e, Aristotle) is here more like a puzzled inquirer 

^Eth.nic. 1113614 £E: 

'This chapter is reprinted (with slight changeB) from the Philosophical 
Review (Vol. XI., No. 3, May 1902). 



(airopoSvTi) than a teacher."^ And Theophrastus, who 
succeeded Aristotle as Scholarch of the Lyceum and was 
intimately instructed in the Peripatetic doctrines, although 
he accepted the theory of a twofold reason (active and 
passive), was unable to explain it. How the reason could 
be at once native to man and yet enter from without, and 
how potentiality is related to actuality in reasoning, were 
difficulties which Theophrastus, as reported by Themifitius,* 
regarded as serious, if not insoluble. Thus the question 
regarding the nature of the active reason' early became a 
matter of controversy, and it has continued a fruitful source 
of polemics among the Syrians, Arabs, and Christians for 
well-nigh two millenniums. 

Eudemus explained the active reason in us by saying 
that it is God (not Oeiov but deoV) in man (cf. Eth, Eud, 
1248a 24). Similarly, Alexander of Aphrodisias (called 
Aristotle's exegete par excellence), who held a pantheistic 
view of the world, regarded the creative reason as the 
activity of the divine intelligence.* The Syrians and Arabs 
were greatly influenced by Alexander. Avicenna, however, 
interprets the doctrine in terms of an emanation theory of 
the world, akin to Neo-Platonism. Intelligible forms are 
endowed with immaterial pre-existence in pure spirits, the 
highest created intelligences. From the highest they pass 

^ ThemistioB, Comm, in Arist. lib. de anima, fol. 716. 

^ ThemistioB, Partxphranis lUnrorum de amma, ed. Spengel, pp. 189, 8 ; 
198, 13. (On De an, IIL, 5.) 

' The term voOs xohjtik&s occurs nowhere in the writings of Aristotle, bat 
the equivalent is given in rd iroiijTiKdif and rd Toi€tp wdrra and hj implica- 
tion in the antithesis to roCt TaBrp-iK&t. Cf. De an. 426a 4, 490a 12, 

* Cf. Brentano, Die Psyckologie des AriMoteles, Mains, 1867, p. 7. 


into a seoond sphere, from the second into a third, and 
so on down into the last, which is the creative reason 
(vntelMgentia agevs). From this creative (cosmic) reason "^ 
intelligible forms pass into the soul, on the one hand ; as 
substantial forms they pass into material things, on the other 
hand. Subject and object are thus reconciled by means 
of the forms (intelligible for reason and substantial for 
concrete things) which emanate from a common source, viz. 
the creative reason. The substantial form, i.e. the class- 
notion immanent in sensible particulars, is correlated with 
the intelligible form, i.e. the concept immanent in reason, 
and therefore knowing subject and known object are only 
different aspects of one reality. Subject and object are ^ 
unified in the creative reason. The passive reason, by 
means of phantasms or images, is able to apprehend the 
substantial forms (genera), and from the active reason it 
receives the light of intelligible forms (concepts). The 
intelligible forms from the active reason are combined in 
the passive reason with the sensible forms, and erected into 
the structure of empirical science. Every act of knowing 
implies receptivity from this dual source of emanated 
forms — intelligible and substantial forms: a curious mix- 
ture of Aristotelianism with Neo-Platonism. 

Averroes, the foremost Arabic exegete of Aristotle, and 
one of the most important intellectual figures of the Middle 
Ages, regards both the active (intellectua a^ena) and the 
passive reason (intellectus Tnaterialis) as spiritual entities 
distinct from the body and from each other. The former's 
activity consists in making sensible images intelligible, and 
thereby moving the passive reason. The passive reason 


receives the phantasms which have been illuminated and 
made intelligible by the active reason. This dual reason 
(consisting of two separate entities) is the eternal in man ; 
while the other powers that are concerned with the par- 
ticular originate with the body and perish with the body. 
In the interpretation of Avicenna, on the contrary, only 
the creative reason is eternal; while the passive reason, 
depending on the life of sense-experience, perishes with the 
body. In the interpretation of Averroes, although the 
reason is immortal, individuality ceases with death; for 
differences in individuals are due to differences in their 
accumulated sensible images and phantasmata — in the 
content of their experience. Rational activity, as such, is 
universally the same, and it is 'only this universal, non- 
individual principle of reason that persists after death. 
All individuals are alike in participating in one rational 
life, and they are different in so far as reason has a 
different mass of images to illumine. The principle of 
individuation is in plastic matter, not in generic form, and 
reason is related to sensible images as form is related to 

Trendelenburg,^ in the commentary to his edition of the 
De anima, explains the passive reason as the sum of all 
the lower cognitive faculties, including the power of 
sense-perception. It is passive because it stands in the 
relation of receptivity to the object of cognition and is 
affected by it. The completion of its processes is, however, 
obtained only through the agency of the active reason. 
The derivation of the universal notion from particular 

^ Of. GommenUry on De an, IIL, § 6, 2 ff. 


sensations is a function of the passive reason, in so far as 
the universal notion is regarded as part of the mind's 
content. The creative reason furnishes the ultimate prin- 
ciples of knowledge, i.e. it contains and applies the standard 
of truth and falsity in the conceptual world as the 
' common sense ' passes judgment on the true and false in 
perceptual reality.^ The creative reason is not the divine 
spirit (although it is related to the divine), but belongs to 
the individual, and is not the same in all men. The rela- 
tion between the divine spirit and the creative reeuson in 
man is nowhere explained by Aristotle, beyond his saying 
in the Metaphysics that they are analogous principles.- 

Ravaisson, in his Essai sur la m^taphysique d'Ainstote,^ 
says that the individual man, according to Aristotle, has 
only passive reason, which as the potentiality of all forms 
and ideas is analogous to primary matter. It is the uni- 
versal potentiality in the world of ideas. On the other 
hand, the creative activity which actualizes possible forms 
and produces all thoughts is the absolute reason. The 
sensible and the passively rational are fundamentally the 
same ; both exist in a single consciousness, and are operated 
on by the active reason. The entire passive reason (and so 
all individuality) is mortal. The creative reason is con- 
ceived by Ravaisson in the same way as by Alexander 
of Aphrodisias. Renan* regards Aristotle's conception of 
the creative reason as similar to Malebranche's theory of 
seeing things in God, — a conception suggested to Aristotle^ 
perhaps, by the Anaxagorean doctrine of Nous. 

1 Cf. Aristotle, De insom. 4616 2 tL > Meiaph, 10726 18 ff. 

'Vol. L, pp. 586 ff. ^Brentano, op. cit,, p. 34. 


Zeller considers the passive reason to mean the " sum of 
those faculties of representation which go beyond imagina- 
tion and sensible perception, and yet fall short of that 
higher thought which has found peace in perfect unity 
with itself.*'^ It does not include the powers of sense- 
perception, as Trendelenburg thinks, nor is it identical 
with " fancy as the seat of mental pictures," as Brentano 
supposes.^ Von Hertling, in calling the passive reason 
** the cognitive faculty of the sensitive part," * would 
almost seem to identify it with the aensiua communia, 
Zeller rejects these and all other explanations of Aristotle's 
theory, and wholly abandons the reconciliation of the 
twofold reason in one personality. He further considers 
it entirely unjustifiable, even in Aristotle's own theory, to 
apply the term notis to the ' passive reason.' Reason, he 
says, is in its essence "a single immediate apprehension 
of intelligible reality, constituting one indivisible act,"* 
which it is not possible to interpret in terms of Aristotle's 
dual theory. 

Wallace, whose interpretation of Aristotle is somewhat 
coloured by English Hegelianism, says : " Aristotle would 
seem to mean that while our intellectual powers are on the 
one hand merely receptive — while they merely elaborate 
and, by processes of discursive thought, systematize the 
materials of thought — these materials of thought only 
become so, only get formed into an intelligible world, by 
an act of reason which has gone on from the creation of 

' Zeller*8 Aristoae, Eng. tr., Vol. II., p. 102. 

'Zeller, op. cit,, II., p. 103. ^ Von Hertling, AfoUerieund FortHf p. 174. 

^Zeller, op. cit., II., p. 105. 


the world and is in turn employed by each of ub. Shortly^ 
then, the creative reason is the faculty which constantly 
interprets and, as it were, keeps up an intelligible world 
for experience to operate upon, while the receptive reason 
is the intellect applying itself in all the various processes 
which mi our minds with the materials of knowledge/' ' 

The foregoing account of Aristotle's theory of reason^ 
as interpreted by his most notable commentators, exhibits 
very wide differences of opinion. This great diversity is 
due to the character of the data furnished by Aristotle 
— data that are both meagre and ambiguous, precluding 
the possibility of any apodictic formulation of his doctrine. 
There has been no lack of ability or ingenuity expended 
on it. It is entirely hopeless, in my opinion, to try to 
discover any satisfactory explanation of the creative reason 
in the scanty passages of the third book of the De anima, 
to which attention has been too exclusively directed. An 
explanation, if it can be found at all, can be found only in 
the light of Aristotle's general system of philosophy, and 
more especiaUy in the light of his complete theory of know- 
ledge. I shall proceed at once to make my me€bning plain. 

It is clear that the theory of a t wof pl d reason, as Aristotle / 
held it, originated partly in the controversy regarding the 
distinction between conceptual and perceptual knowledge,, 
and partly in Aristotle's metaphysical ideas regarding the 
distinction between form and matter. The controversy 
touching conceptual and perceptual knowledge had before 
Aristotle's time issued, on the one hand, in the extreme 
sensualism of the Sophists, and, on the other hand, in the ^ 

^ Wallace, ArisUMs Psychology ^ p. xoviii. 




extreme rationalism of Plato. Between these two Aristotle 
adopts a mediating position of empiricism. To him there 
are no innate ideas, and no body of rational truth totally 
independent of particular reality. All knowledge is per- 
ceptually derived, but the materials of perception cannot 
be converted into the fabric of scientific knowledge or into 
general concepts without a creative and supplementary 
act of reason. For Aristotle, as for Kant, conception with- 
out perception is empty. The content of perception is 
^made into conceptual knowledge by a process of reason, 
and in this sense is a created content. Before this act 
takes place, the content of mind is passive matter awaiting 
a transforming and constructive process. At this point, 
Aristotle applies to psychical life the metaphysical dualism 
imder which he views the entire organic world. Active 
refiuson stands to passive reason in the relation of form to 
matter.^ His metaphysics, then, and the distinction between 
conceptual and perceptual knowledge, explain the genesis 
of his theory of a twofold reason. The creative reason is 
the form-principle ; the pathic refiuson is the sum of matter 
that is formed into rational significance. Keason receives 
its content from without; in other words, it is passive. 
However, if that were all, reeuson would be only a receptacle 
of sensations, perceptions, memory-images, and phantasmata. 
But transcending these pathic elements, reason has the 
informing power of changing their potentiality into the 
highest abstractions and most general notions and laws. 
In this way, reason, in its pathic aspect, becomes or receives 
all reality; while in its active character, it creates all 

1 De an. 4d0a 10 ff. 


reality by bestowing upon it a rational form. Without the "^ 

latter the mind would be a mass of particulars, of unrelated 
manifold things, blind. The active reason creates an^ 
intelligible world in the sense of constructing its intelligi- 
bility, while its real content is given in the materials of the 
passive reason which are delivered from without. This 
content is potentially conceptual. The creative reason is N 
thus primarily without content, an unwritten tablet.* 
Between conceptual and perceptual knowledge, between 
the abstract and concrete, there is not for Aristotle the 
great impassable gulf that we find in Plato's epistemology. 
Although the discovery of the imiversal is an act of reason, 
yet the universal is potentially and immanently in the 
individual. The subject-matter of reason is the immanent 
universal, which in a certain sense is in the mind itself.* 
Thought and sense-perception are neither identical nor are N 
they to be completely sundered. Aristotle sharply criticises 
both of these extremes in his predecessors, holding the 
sophistic sensualism and Platonic rationalism to be equally 
one-sided and erroneous. In thought we think, it is true, 
what is potentially given in perception, and yet this object 
of thought must first be made rational by a creative act of 
reason. Reason creates its world in terms of itself (i.e. a 
rational world); and, as its subject-matter consists of 
abstract ideas, it thinks itself, and subject and object are 
identical^ Aristotle is not a pure empiricist, although in 
certain paj9sages he speaks as if all our ideas were derived 
from sense-perceptions* and apart from sense-perception 

1 Dt an. 4dOa 1. <Z>e an, 417623. 

*Dt an, 429a 25, 430a2, 4316 17. *De an. 432a 2ff. 



there were no reality. In the AncUytica, however, where 
he gives the most detailed account of the origin of our 
knowledge, he speaks of the highest principles of knowledge 
as immediate (ra a/jLea-a) and as presupposed by mediately 
derived knowledge, being the latter's starting - point.* 
These ultimate principles are propositions whose predicates 
are given in. the subject, i.e. 'analytical a priori judg- 
menta'* This knowledge is, however, merely potential 
(empty conception) until applied to the content of experi- 
ence. It does not contain any positive ideas, but, as in 
the case of the principles of contradiction and excluded 
middle, it comes to consciousness in the regulation and 
determination of cognitive data. These regulative, axiomatic 
principles are formed by the mind out of itself.' The 
content of the concepts arrived at by induction, or by an 
ascent from particular to general, takes the form of mediate 
knowledge; and the most universal of these concepts ia 
only a "precipitate of a progressively refined experience, 
and is due to the last act in successive generalizations upon 
a matter given in experience."* Ideas derived from in- 
duction attain a degree of certainty not higher than the 
source from which they spring. On the other hand, the 
ultimate principles (apxcu) of reason are necessarily true,^ 
and such knowledge has the nature of an " intuition aa 
contrasted with sensible perception." • The apodictic 
syllogism, or highest form of scientific truth, proceeds from 

>Cf. Zeller'B Aristotle, Eng. tr., Vol I, p. 197. Also AriBtotle, Anal^ 
pom. 86636, 94a 9, 10868; EtK tiic. lUlo. 

'Zeller, op. cit.. Vol. I, p. 198. »Z)e on. 429628 flf. 

*Zeller, op. cU., Vol. I, p. 201. » Arifltotle, Anal. poBt. 10065 £f. 

<^Zeller, op. cU., Vol. I, p. 202. 


reality by bestowing upon it a rational form. Without the ^ 

latter the mind would be a mass of particulars, of unrelated 
manifold things, blind. The active reason creates an^) 
intelligible world in the sense of constructing its intelligi- 
bility, while its real content is given in the materials of the 
passive reason which are delivered from without. This 
content is potentially conceptual. The creative reason is N 
thus primarily without content, an unwritten tablet.^ 
Between conceptual and perceptual knowledge, between 
the abstract and concrete, there is not for Aristotle the 
great impassable gulf that we find in Plato's epistemology. 
Although the discovery of the universal is an act of reason, 
yet the universal is potentially and immanently in the 
individual. The subject-matter of reason is the immanent 
universal, which in a certain sense is in the mind itself.* 
Thought and sense-perception are neither identical nor are '^ 
they to be completely sundered. Aristotle sharply criticises 
both of these extremes in his predecessors, holding the 
sophistic sensualism and Platonic rationalism to be equally 
one-sided and erroneous. In thought we think, it is true, 
what is potentially given in perception, and yet this object 
of thought must first be made rational by a creative act of 
reason. Reason creates its world in terms of itself (t.e. a 
rational world); and, as its subject-matter consists of 
abstract ideas, it thinks itself, and subject and object are 
identical* Aristotle is not a pure empiricist, although in 
certain peuBsages he speaks as if all our ideas were derived 
from sense-perceptions* and apart from sense-perception 

1 Dt an. 4d0a 1. <Z>e an, 417623. 

>i>e an, 429a 25, 430a2, 431617. *De an. 432a2ff. 


creative reason makes the the universal forms intelligible. 
Or, to use another analogy employed by Aristotle, the 
creative reason operates on the content of perceptual con- 
sciousness as an artist operates on his raw materials.^ The 
two main stages in the process of knowledge, perception 
and conception, are supplementary. Thought, on the one 
hand, requires a sensuous image,' and perception, on the 
other, remains on a brute level when not illuminated and 
elevated into conceptual form by reason. 
<rThe creative reason is akin to the divine. Corresponding 
with his metaphysical conception of the divine in the 
universe, Aristotle regards the creative reason as the divine 
in the microcosm. It is no paji) of the entelechy of the 
body, but is transcendent (xa>p<<rro9> i'^- it has no bodily organ 
and is separable from organic life) and it enters the body 
from without (dvpadev),^ It acts, however, on the rational 
life of the organism, but it acts as the ' unmoved mover,' 
who is immanent in the world without being a part of it. 
'^ The creative reason is not developed with the body, but 
enters the psychical element (whose immediate corporeal 
embodiment is the warm air or pn&wma in the seed) at the 
moment of conception. Conception is the occasion, not the 
cause, of its entering into the womb.^ The question, how- 
ever, touching the preexistence and immortality of the 
soul is scarcely more than mentioned by Aristotle, and, 

1 Dt an, 430a 12. ^De an. 431a 17, 432a 8 ; Dt mem, 4496 30. 

* De gener, anim, 736627 ff. 

*De gener, anim, 737a 5 £f. Granger in a valuable article in Mind (VoL 
18, New Series, VoL 2, 1893, p. 317) thinks that a oniversal reason in 
Aristotle's psychology can be spoken of only in the sense in which one 
speaks of "a universal humanity." Of. the same writer in the OUuticcU 
Review^ VoL VI., pp. 298 £f. 


indeed, it hardly falls within the scope of his psychology, 
which is an essentially biological discussion. It is only in 
treating of the nature of reason that he goes beyond the 
boundaries of empiricism and makes concession to the 
traditional view of the divine origm of the noetic power — 
a concession that may have been prompted by his analo- 
gous view of the Prime Mover as the transcendent cosmic 
reason. Aristotle constructs his psychology, as he does his 
entire system of philosophy, on the basis of the deliverances 
of the special sciences of his day — deliverances which were 
penetrated and interpreted by his unifying and organizing 
spirit. As Romanes says, '' instead of giving his fancy free 
rein ' upon the high a priori road,' he patiently plods the 
way of detailed research/'^ Yet, after he has completely 
examined the data and psychical mechanism of empirical 
knowledge, he finds them inadequate to explain the whole 
of reality, and is forced to introduce a rational ego to 
explain the potential rationality of pathic experience. 
This noetic principle which rationalizes experience is in no 
wise connected with the physical organism, 'and as it is 
not a part of the latter's entelechy, so it does not perish 
with its dissolution.^ It is the a priori condition of all 
rational knowledge, and, as such, it is not individual. 
Receptive or pathic reason,* on the other hand, is simply 

1 CorUemporary Bevieto, VoL 59, p. 284. ^Dean, 4086 18, 4136 20 ft 
' No one familiar with Aristotle's ase of terms, will discover an objection 
in his applying two designations to the same thing, viz, to his calling the 
sum of perceptual experience now aensua communis^ and again passive 
reason. For as completed sense-experience, the 9en9U8 communis is form 
(ei^ot), and as the raw material for some higher development it is poten- 
tiality {C\ij), That higher development is reason, which the common 
sense m potentially. 


the life of sensation as a potentially rational mass, and is 
connected with the physical organism, with which it 
perishea^ Primarily, the creative reason is, as above noted, 
¥dthout content ; it is an unwritten tablet (ypafAfwreiovy 
Its content is given in the passive reason, which is stored 
with phantasmata ultimately derived from sense and the 
free construction of imagination. Strictly speaking, the 
active reason does not think things, it does not create de 
novo; it merely interprets things, or rationalizes pheno- 
mena, by its spontaneous activity.^ Nevertheless, we have 
here not merely that which is given in sense-experience, 
but a new element, rationally derived, a new significance. 
Passive reason rises no higher than the deliverances of 
sense-perception and their re-wrought form in memory and 
phantasy. The sum of these is the sum of the content of 
the 8e7isu8 cormnunis ; this sum, regarded as potentiality, is 
the passive reason, on which the active reason operates in 
the creation of a rational and conceptual world. The 
creative reason does not, indeed, think anything apart 
from the passive reason,^ because without images derived 
from experience thought has no content and nothing to 
interpret or illumine. Its activity, however, is continuous,^ 
because its subject-matter, unlike a sense-object, is always 
present. Further, as the universal reason, it is as eternal 
and continuous as is the intelligibility of the eternal world.^ 

'Dean. 4d0a 25. * Z><! an. 4d0a 1. 

'Cf. SootoB : '' nalloB intellectoB inteUigit, nisi intellectus postibilis. . . . 
[intelleotoB agens] non intelligit, sed intelligere facit." Qaoted by Sohlott- 
mAnn in Dm Vergdngliche tmd Unverg&ngliche in d, meiuchlicken 8ede 
nach ArisL p. 48. 

« i>e an. 430a 25. "Dean. 430a 22. • Z>e ocefe, 2796 12. 


We do not remember ^ the processes of the active reason — 
an understanding of which in the individual is arrived at 
only by analysis — because it is without passivity, and 
memory is a passive power. 

Aristotle describes the creative reason (I draw from 
various passages) as follows : it is unmixed, transcendent, 
passionless, of divine nature, it suffers no change, is not 
bom, it has no bodily organ, enters the body from without, 
and is immortal' The question of the reason's transcend- 
ence and immortality, although metaphysically interesting, 
has little epistemological significance, and Aristotle scarcely 
does more than raise the question, and while he espouses 
the view of transcendence and immortality, he does so 
hesitatingly and without dogmatism. Transcendence, in- 
deed, would seem to have no legitimate place in his 
biological view of the soul and to be irreconcilable with 
his definition of V^i/X'7 ^ '' entelechy of the body/' It is a 
survival of the Platonic transcendentalism, with which 
Aristotle had been imbued during his Uf e in the Academy, 
and whose spell he never quite shook off, — a thing to be 
set down to his credit. 

In the foregoing account of Aristotle's theory of reason 
I have endeavoured to show how his employment of the 
terms 'form' and 'matter' and his criticism of the 
Socratic-Sophistic controversy regarding conceptual and 
perceptual knowledge can be made to supplement certain 
dark passages in the De anima and the Analytics, and how 

1 De an. 490a 23. 

>Z)e an. 40661829, 413624, 430a 12C; Mh. nic. 1177a 15; De gen. 
omm. 736615 ft 


these various elements can be combined into an intelligible 
and consistent interpretation. Briefly summarized, this 
' / interpretation is as follows : Aristotle adopted a mediating 

position between the ultra-sensualism of the Sophists and 
the ultra-rationalism of Plato. The totality of knowledge 
is neither purely empirical nor purely rational, but a com- 
posite (arvvoXov, as is every other combination of ' form ' and 
' matter') of sense experience and rational activity. In this 
composite, rational activity is related to sense-experience as 
eJSo^ is related to vXtj. The sum of sense-data constitutes the 
potentiality of reason, i.e. it constitutes the passive reason, 
while their construction into actual rational significance 
constitutes the activity of creative reason ; the real content 
is given in the former, the formal content in the latter. 
The content, therefore, of the sensua communis regarded as 
rational potentiality is the voS^ TradfiriKo^ ; the power which 
converts this potentiality into actual rational forms or 
meanings is the 1/01/9 iroirp-uco^. This conversion is identical 
with the erection of perceptual materials into a world of 
concepts and laws. The subject-matter of reason is an 
^ x^^ immanent universal, — immanent at once in perceptual 
,^^ reality and in the reason itself. The process which the 
reason undergoes in discovering the universal is, therefore, 
the process of finding itself in the world. The conception 
of an equivalence between the universal forms existing in 
the mind and universal forms immanent in nature bridged 
for Aristotle the gulf between subject and object, — ^two 
aspects of reaUty which he regarded as formally identical. 


[ ] = words regarded by Biehl as not belonging to the text and to 
be deleted. 

([ ]) = words inserted by the translator. 

The marginal references, e.g. 402a, are to the pagination (with colnmn 
a or b) of the Berlin (quarto) edition. The other marginal references, e,g. 
2, 3, 4, are to the sections in the chapters of the Oxford (octavo) edition. 





We regard knowledge as a good and precious thing, but 402 a 
we esteem one sort of knowledge more highly than 

^ Bonitz regardfl the various chapters of De an. Bk. L as Aristotle's, 
although he thinks that the order in which they are placed is due 
to another hand {AfoncUshericht der KOnigL Prewa. Akad. d. Wiaa.^ 
1873, p. 481). The authenticity of Bks. I. and II. has never 
been seriously questioned. Bk. III., however, was held by Weisse 
to be spurious {Aristotdes von der Seele, pp. 278 ff.), but no scholar 
now, to my knowledge, accepts his view. The Aristotelian canon 
is much less questionable than the Platonic, and, as far as the 
acroamatic writings are concerned, has always remained compara- 
tively fixed. The objection of Bonitz to Bk. I. scarcely means 
more than that its Aristotelian content was subjected to editorial 
arrangement, which was not always skilful, — a criticism that may be 
applied to every other treatise in the Opera, To attempt to determine 
how much latitude Andronicus and the succeeding editors allowed 
themselves, is merely to speculate. All of the works, without exception, 
are fragmentary and ill put together, but this has been explained 
generally by the time-honoured hypothesis (and still the most reason- 
able one) that the writings of Aristotle, as we have them, are lecture- 
notes or perhaps sketches for treatises, which he never put into 
finished form, the last part of his life being disturbed by quasi- 
religious penecution and spent practically in exile. 



another either because of the acumen ^ required for its 
discovery, or because it is concerned with better and 
more admirable objects : for both these reasons we 
ahould rightly assign the investigation of the soul ^ to the 
first rank. Further, it is supposed that a knowledge of 
the soul has an important bearing on all truth, and par- 
ticularly on that of the natural world. For the soul is, 
a as it were, the genetic principle ° in living things. Our 

' This meaaiug of eot' inpiffftar appears to be the only one odnusBible 
in tbe context. C(. Poasow, lab vac. Tba meaning which the term 
bos when applied to metaphysical or sbstraot sobjecta [Etli, nit. 1141a 
16; MUaph. •iiia 25, 107Sa 10; Anai. post. 86a 17}, viz., 'exacti- 
tude' in tbe eenM of ' fioally true' or truth deduced from the Aral 
principteB of reality, is uot applicable htire. Aristotle reyardB the 
materialii of psychology aa belonging to the natitral and orgonia world, 
which to him Is never the realm of oeceaaary or exact truth. 'Axpipna 
in the ordinary seme of ' precision ' is ascribed to the mathematical 
discipliuea is varying degrees {Jil<ii, 1053a 1, 9S5a 15; Anal. po*l. S7a 
3fi), bat this sense is also inadmiBsiblc here (cC. 402a II}. In addition 
to those meanings which refer to the science itself, tbe word also has k 
■igaificatiDn which refen to the demand made by the wienoe on the 
investigator, viz., ' paiostaliiiig accuracy,' or 'acumen' (' Scbarfsinn,' 
Fassuw}. In the present paBsage this appears to be the only usable 
meuiing. Vid, Wallace, Ariatotle'i Feycludogy, p. 196; Trendelenbarg, 
ArUt. De on. Snd ed. p. 150. 

'ifiux'l ('soal,' 'life,' 'mind,') is generally translated in the following 
pages by 'aoul.' For a diacusaiou of its meanings in AnttaUe'a 
writings vid. Introduction, Chap. i. 

' '^PX.'h l/Tinci/xurn) ia included amongst the notions defined by 
Aristotle in his philosophical dictionary iJUetaph. Bk. V.). Throngh 
him it became a philosophical term of the first importance, and bos con- 
tinned so to tbe present time. In the sense of element {rraxdor) we 
find it in use as early aa Anoximander, The meanings enumerated in 
the Melaphynta are: In refereuce to (1) space and time - beginning ; 
(2} method - elementary steps in learning ; <3) tlie physical = basis ; (4) 
the genetic^the moving cause; (5) the political^primary authority; 
(6) knowledge -jmndpium cogaoaeeHdi, as e.g. the premises ot a 
■yllogism. Tbe scholaslice iocladed these several meanings under 
prineipium tustndi and principium toi/nauttuti, for which Aristotle has the 
•Orrespouding enpression, ts* 7>uvai lal r^t tiv^eian ipxi i^'t. 1013a 22). 


I aim is to investigate and ascertain the essential nature 
I of the soul, and, secondly, to discover those properties 
which attach to it as accideots. Certain of the latter 
are supposed to be conditions peculiar to the soul's own 
nature, and others are thought to be effects produced in 
living beings by the soul's agency, 

Now, it is altogether the most difficult problem 3 
to arrive at any hxed belief touching the soul. From 
the fact that the problem is one which is common 
to other subjects — I mean the problem of finding the 
essence and real definition ' of a thing — it might perhaps 
appear to some that there is a single scientiiic method 
which applies to everything whose essence we wish to 
discover, as deductive proof applies to accidental pro- 
perties. We shall, therefore, be obliged to make inquiry 
into this question of scientific method. But if there is 4 
no single and general method which applies to the 
ultimate nature of things, our investigation becomes in 
that case all the more difficult. And even if the 
' question of method were cleared up, whether it« form 
be that of deductive proof, or analysis, or some other 
' procedure, there still remains a question of great diffi- 
I culty and uncertainty, viz. from what principles are 
we to start our inquiry ? For difTerent principles are 
I employed in diETerent subjects, as K.g. in numbers* and 
in plane suriaces. 

The first necessity, perhaps, is to determine under 5 

'For the moaning of ri rl lirri sse Schwegter's clusic eiourBUH in 
. hi%Dit Mttapkyai)i:de»Ari»MtUB,Bk.lV.,^.Z&%S. Also Trendaleo- 
I bai^ in Bhanii-chtJi Muttvm, 1828, pp. 457 ff. 

'The lUffereat principle! employed bjMitbmatia Mid geometiyan 

I the onil and eitenBiou. 


\ J' what genus soul is to be classified and what its nature is 
— I mean by this the question whether it is an individual 
thing and aelf-subsisting entity, or whether it is a quality 
or a quantity or classi&able in one of the other cate- 
gories ' already enumerated, and further, whether it is a 
potentiality * or rather an actuality. For this makes no 
m slight difference. We must also inquire whether the 

6 soul is divisible or whether it is without parts ; whether 
it is an entirety of one sort or not. And if it is not of 
one sort, we must further ask whether the differences are 
specific or generic For nowadays the men ^ who discuss 
and investigate the soul appear to direct their inquiries 

7 merely to the human soul. We must take pains to see 
whether there is a single definition that applies to the 
soul, just as e.ff. there is a single definition that applies to 

', animal, or whether a different definition is required for 

^ each kind of soul, just as a different definition is required 

for horse, dog, man, god, and we must further inquire 

whether the common notion ' animal ' * either is nothing 

' The categories or fomu aa<]er which Being is known, iLre enumerated 
in the Topica {103b 22) aa folton-a : 1. t^ubBt&ooe, 2. Quuititj', 3. 
Quality, 4. ReUtbn, 6. Ptkce, fl. Time, 7. Poaitiaa. 8. PoiKnion, 9. 
Acldvity, 10. Piwainty. All of tfaem are reducible to suLjeut {Uroixa, 
oomnponding to the category of 'subctuice') and predicate (^$ua, 
ootTesponding to the nine remaining categories), 

* For on explaoatioD of the tenita potentiality and actuality iiut, note 
1, p. K. 

'It is not known to whom referenue is made here. Simpliciua 
{Commtnl. in lib, Dc an. ad toe.) thinks the Timaeui a referred to, 
which ie hardly possible owing to FUto'n treatment of the world-HOul. 
Kor is it easy to see how Wallace (traDslating tir fiir by " at present " 
I H he does), can sappose the raference is to the older physiologera. 

*The question as to the nature of anivemtlH, which divided tlie 
Hsdioeval Nominoliata and Bealista, was here eleorly railed by 
Aristotle. Vid. Simplicius, Commentary ad lot. 

the fs 


bII or else comes into existence only after the indi- 

lual, — a question that might equally well be raised 

'yarding any other general notion. If, however, there 

ire not several souls, but only parts of a single soul, then 

the further question arises whether we should examine 

soul as a whole before we examine the parts. It 8 

also hard to determine which of these parts is in 

nature different from the other and whether we 

luld first investigate the part or the part's function, 

whether we should first investigate the process of 

ight or the faculty of thought, sense-perception or 

organ of sense-perception ; the same question applies 

other cases. N'ow, supposing that the functions take 

lence of the faculties in the order of investigation, 

further question might arise here as to whether the 

complements of the faculties should be investigated before 

the faculties themselves, e.ij. whether the investigation of 

le sensible object should precede the investigation of the 

■organ, and the object of thought precede the faculty 

thought. Not only does the knowledge of the 9 

essential nature of a thing seem to he helpful towards 

the understanding of the accidental nature and properties 

of substances, just as in mathematics the knowledge of 

the essential nature of straight or curved or of a line 

or surface is helpful in understanding how many right 

;les are contained in the angles of a triangle, but 

inversely, the knowledge of accidental properties con- 

jbutes largely to the understanding of what a thing 

essentially is. For when we are able to give an 

account of the accidental properties of things, as we see 

lem,— either of all these properties or of most of them. 


—then we are best able to speak also of their essential 

nature. For the i 

iDtial nature 

the I 

s atartiiig- 

poiut in all deductive proof. And so in the case of 
deGnitions where not only no knowledge of the accidental 
properties is furnished, but where it is not easy even Ut 
4030 conjecture what these properties are, it is evident that 
all such definitions are ^med after the fashion of 
dialectics ' and are void. 

10 A further difficulty presents itself r^arding the 
affections of the soul, viz. whether all these affections 
are common to the soul and to the body which contains 
it, or whether there is a something that is the exclusive 
property of the souL And it is necessary, though not 

11 easy, to solve this difhoulty. In most eases the aoul 
apparently neither acta nor is acted upon independently 
of the body, e.g. in the feelings of anger, courage, desire, 
or in a word in sense-perception. Thought, however, 
appears to be a function which more than any other 
is the exclusive property of the soul. But if thought 
is a sort of representation in terms of a sense-image, or 
is impossiblB without this, then even thought could not 

12 exist independently of the body. It', then, there were 
any function or affection of the soul that were peculiar 
lo it, it would be possible for the soul to exist separate 
and apart from the body.* If, however, there is nothing 

' I.t. dutinotioui thai mode are merely verbal or eriatiu and have no 
real coateat. 

'The difficalt questioa us to whether the aoul ii capable of existing 
Mparntely from the hody U not very clearly or dofinitoly answered 
by Ariatotlu. According lo Ariitotle'a clauic definition, tbe soul ii 
the "entolwihy of a body endowed with the capacity of life." From 
this definitioD one would conclade that the soul cannot exist apart from 


I which ia its exclusive property, it cannot exist apart, but 
1 the case is Himilar to that of n etraight line, which, as 
f straight, has many properties, e.g. contact with a bronze 
};lobe at a given point, although the quality 'straight,' 
apart from some body, does not touch the globe. For 
I it has no abattact existence, as it is always conjoined 
f with some body. The same thing seems to hold good 13 
I of the properties of the soul : courage, gentleness, fear, 
I pity, audacity, also joy, love, hate ; they are all associated 
f with the body. For along with these psychical con- 
ditions the body is also somewhat affected. A proof 14 
of this ia the fact that sometimes when great and 
palpable misfortunes have befallen a man, he is not at 
all excited or moved to fear ; on the other hand, one is 
sometimes aroused by slight and insignificant mishaps, 
and then the body swells in rage and is in the same 
condition as when a man is stirred in anger. But this 
statement receivas still more support from the fact that 
i^hen nothing has happened which could awaken fear, 
exhibit those emotions which characterize a man 
in fright. And if this is true, it is evident that the 15 

the body, sltboagh it is uot itself cnrporeftL It is that which gives 
to a partiualu bcxly its individuality and meBDing, and it vonBiBts of 
the following elementa : power of nutritioD, self- movement, senBation, 
memory, emotioa, iinagiDBtioD, and reaaon. AmoDgst these fanutioiiB 
of the soul, rea«OD a peuuliiir to msn, although reuoD in its paBsive 
fonn is baipd on aenBibte experience and is conjoined with the life of 
the body. There is, however, • further form of reason, which Aristotle 
characterizcB as active reason (vsOf a-onir-iidr), whose existence is entirely 
separable frooi the body, and is immortal {Be an. 403a 23). This form 
of reason is conoernsd with intoitioa or immediately apprehended 
truth, while the patmive reason is occupied with mediated truth. Tliere 
teems, however, to be DO plooe for the former in ArUtotle'a detuiition 
of the soul cited above. Cf. Introduetion, On the Anlive and PoMnvt 


emotions are ideas wliich find expression in the body. 
So that we have, for example, such definitions as the 
following : " Anger is a kind of movement of such and 
auch a body, or part, or faculty, under this or that 
stimulus and due to this or that motive." It is for 
this reason that the study of the soul belongs to the 
province of the natural philosopher, either the soul in ita 
entirety or such part of it as has to do with the body, 

i6 But the naturalist and the speeulative philosopher would 
frame their definitions severally from different stand- 
points. For example, in reply to the question A What 
is anger ? " the speeulative philosopher says it is the 
desire of retaliation or something uf that sort, the 
naturalist says it is the seething of the pericordial blood 
403* or heat; the one has furnished in his answer tlie matter, 

17 the other the form or reason, of the thing. For the 
notion is the form of a thing, and it is necessary that 
this notion be embodied in a particular matter, if it is 
to exist. For instance, the notion of a house is that 
of a shelter, to protect ua against injury from wind and 
rain and heat; the natural philosopher, however, will 
call it stones and bricks and wood, while the other 
grasps the notion embodied in these things and for which 

iS they exist. Which of these, now, is the real physical 
phitoaopber ? Is it the one who busies himself with 
the matter, but is ignorant of the notion 1 or is it the 
inquirer who is occupied with the notion alone ? I 
answer, it is rather the man who combines both of 
these characters, "feut what is the genius of each of 
these two men T ourely there is nobody who concerns 
himself merely with the properties of matter that are 


inseparable and merely as inseparable; but the physical 
philosopher has to do with all the functions and qualities 
of body and matter which are of such and such a kind. 
Such properties as are not subject-matter for the natural 
philosopher, are dealt with by someone else, in certain 
instances by a professor of one of the arts, perhaps, as 
e,g, by a builder or by a physician. But in the case 
of properties which are inseparable, although they attach 
to no particular body and may be abstractly r^arded, 
with these the mathematician is concerned ; and in 19 
so far as the qualities are regarded as abstract or 
transcendent entities, the metaphysician is concerned 
with them. But we must now return to the point from 
which our discussion digressed. We were saying that 
the properties of the soul do not exist apart from the 
physical matter of living things, in which such qualities 
as courage and fear are expressed, and are not to be 
regarded as a line or surface. 


In our inquiry into the soul it is necessary for us, as we 
proceed, to raise such questions as demand answers ; we 
must collect the opinions of those predecessors^ who 
have had anything to say touching the soul's nature, in 
order that we may accept their true statements and be 

2 on our guard against their errors. The initial step in our 
inquiry will be to set forth those attributes which are 
currently supposed to inhere in the soul's nature. Ani- 
mate nature is thought to be different from the inanimate 
mainly in two particulars, viz. in movement and sense- 
perception. And these, I may say, are the two 
traditional characteristics of the soul which we have 
received from earlier writers. Some of these writers, 
indeed, affirm that motion is the first and foremost 
characteristic of the soul, and in the belief that what is 
itself unmoved cannot impart motion to anything else, 

3 they suppose that the soul is a moving entity. This 
404 « is the reason why Democritus declares the soul to be a 

sort of fire or warm element He asserts that, although 

^Aristotle begins here the first extant history of psychoiogical 




atomic structures are infinite in variety, both fire and 
soul are composed of spherical atoms, similar to the 
particles, as we call them, seen in the air when sun- 
beams stream through a doorway, and these atoms, as 
collective seed-particles, he caUs the elements of the 
universe. Leucippus also holds a similar view. It is the 4 
spherical atoms, he says, that constitute the soul, because 
such forms can most easily penetrate through everything, 
and, being themselves in motion, can move everything 
else, the theory of these philosophers being that the soul 
is the principle which imparts motion to animals. It is s 
for this reason too that they regard respiration as the 
function that fixes life's limit. They think that the 
surrounding air presses together and expels the atomic 
bodies, which, because they are themselves never at rest, 
impart motion to animals, but that relief comes through 
respiration, because similar particles thereby enter into 
the body from without. These latter, by restraining the 
contracting and condensing element, prevent the spherical 
atoms which are already in animals from being entirely 
expelled. So long as they can do this, life continues. 
The theory which has been handed down from the 6 
Pythagoreans appears to have the same import. For 
some members of this school maintain that the sun-motes 
in the air are the soul; others declare that the soul is 
the principle which sets these in motion. They refer to 
these particles in their theory, because the particles 
appear to be in constant motion, even when there is a 
complete calm« The philosophers who regard the soul 
as a self-moved principle come to the same conclusion. 
For they all seem to regard motion as the most char- 7 

12 Aristotle's psychology deakma 

acteristic attribute of the soul, and while everything else 
is moved by the soul, the soul is self-moved. They came 
to this conclusion because they observed that nothing 
sets anything else in motion without being itself in 
S motion. In a similar spirit Anaxagoras also declares the 
soul to be the principle of motion, and this view is held 
by such others, if there are any, as assert that Beason 
sets the All in motion.^ 

Anaxagoras does not, however, quite agree with Demo- 
critus. For Democritus absolutely identifies soul with 
reason, and considers truth to be that which appears 
to the senses. Consequently, Homer is right in singing 
of Hector that he lay "thinking awry."* Democritus 

^ The pre- Aristotelian definitions of the soul here cited are classifiable 
into three main groups: (1) those that regard the kinetic or motive 
attributes of the sonl as its fundamental characteristic ; (2) those that 
regard the intellectual and cognitive attributes as fundamental ; (3) those 
that attempt to combine these two elements of activity and knowledge. 

'No such reference as this is to be found in our present text of 
Homer, although the term ASXo^tpoviwra occurs in IL zxiii. 698. Cf. 
also Ar. Mttwph, iv. (iii.) 5. 10096 28. The word is here employed in 
the meaning of ' to think incorrectly,' while ^pwtw signifies, when con- 
trasted with dXKo^pov€i9f 'to think correctly.' Hector lies senseless 
from a blow, and as thought, in the psychology of Democritus, origin- 
ates in sensation, his thinking cannot be true, but is paralysed or per- 
verted proportionately to the disturbance in sensation. Error and 
mental disturbance {dXKo^pwtaf) are explained by disturbance in the 
activity of the senses (cf. Siebeck, €^t8chichU der Psychologie, Th. i. 
Abth. i. p. 129 ; Natorp, Forachungen zur OeschichU dea BrhenntniaS' 
prdbUmes im Alterthvm, pp. 171 ff.). Democritus makes a distinction, 
however, between the relative values of rational and perceptual know- 
ledge, between X^tos and aJSj^o-tt, although both originate in external 
stimuli The ultimate, and in this sense the real, nature of things is 
not discoverable by the senses, but only by rational thought. The true 
nature of the world consists of atoms and the void, and these are known 
not to our senses, but to our reasoning mind ; they are wotrrd. The 
data, however, for these rational truths are to be sought in the deliver- 
ances of the senses. 


does not employ reason as a specific faculty for the 
apprehension of truth, but asserts that soul and reason 
are identical. Anaxagoras, however, is less clear on 9 
this point. For although he says in many passages 404^ 
that reason is the cause of the beautiful and the true, 
in other passages he says that reason is the same as 
the soul, for it is found in all animals, great and small, 
high and low. Beason, however, in the sense of intelli- 
gence, is not found equally in all animals, nor even in 
all men. 

Such philosophers as fix their attention on move- 10 
ment as the main fact in animate creation conceive of 
the soul as the most mobile principle. On the other 
hand, such philosophers as emphasize the knowledge 
and perception of reality, define the soul as the 
principle of things, some holding there are several such 
principles, others that this psychical principle is the only 
one. Empedocles, for instance, regards the soul as com- 
posed of all the elements, and he asserts that each of 
these elements is a soul. He says : 

"Earth we apprehend by earth, water hy water, 
And air divine hy air, destructive fire by fire, 
And love we know by love, sad hate by hate." 

In this way, too, Plato in his Timaeus^ constructs n 
the soul out of the elements; for we know like by like, 
and things are composed of elemental principles. A 
similar theory is given in his Discourses on Philosophy^ 

^ TimaeuB, 30 C, 35 A, 39 E. 

'No such work of Plato is known to us, and the reference is pro- 
bably to the oral discourses held by Plato in the Academy. Fid. 
Bemays, Die DicUoge des AriatoteUs, p. 170; Heitz, Die veriorenen 
Schriften dea Aristoteks, p. 180; Zeller, PhU. d, Orieehen, Th. 11. 
Abtb. iL 3te. Aufl. p. 64, note. 



where he defines an animal, regarded absolutely, 
as a structure derived from the idea of unity and the 
primary elements length, breadth, and thickness ; other 

12 things are similarly fashioned. Again, in a different 
way, Plato defines reason as unity, and science as two j 
for the latter moves towards unity in a single course. Ha 
also defines opinion as the number of a plane surface and 
Bense-perception as the number of a solid. Numbers 
were declared to be the actual forma and firat principles 
of things and to be composed of the elementa. But 
things are discerned partly by reason, partly by science. 
partly by opinion, aud partly by sense-perceptioo. 

13 Numbers, however, are the forms of things. Since 
the soul was regarded by these Platonists as at once 
the principle of motion and the principle of knowledge, 
some of them included both these ideas iu their 
definition, and explained the soul as a self-moving 
number.' These philosophers differ, however, in regard 
to the kind and number of their principles. The most 
far-reaching difference ia that between the philosophers 
who regard the elementa aa corporeal and those who 
regard them as incorporeal. There are others who define 

4050 the elements as a composite of corporeal and incorporeaL 

14 They differ also in regard to the number of the elements, 
some believing there is one only, and others that there are 
several, and their definitions of the soul vary with their 
theories of the elements. Amongst the primal elements 
they classified, not unreasonably, the principle of inherent 

' Xenocrktos of ChaloedoD [396-314 B.O.), BDOcesBor of SpeueippuB 
u SchoLuch of the Academy. I'tii. Ueberweg-Heum, OrHiadrui d. 
QiKhkhte d. PhUotophU, Th. 1. p. IBl, Sth eel. 



movemant. And bo some philosophers held the soul to 
be fire ; for fire is the finest and most nearly incorporeal 

l«f all the elements, and furthermore, it most readily 
Bceives and imparts motion. Democritus has expliuned is 
1 a very neat way the cause of these phenomena. Soul 

liuid reason, he says, are identical, and belong to the 
mary and indivisible bodies, and are, furthermore, the 

' principle of motion by virtue of their particles and 
atomic forms. Amongst these atomic forms, he regards 
the spherical as the most easily moved, and says that 
reason and fire are of this sort. Anaxagoras, on the 16 
other hand, appears to say that the soul and reason are 
different, as we remarked above, and yet he employs 

bthem as essentially one, except that he regards reason as 

^more than anything else the initial principle of the 
world. At any rate he asserts that reason is the only 
entity which is absolute, unmixed, and pure. But he 17 
ascribes both attributes of knowledj^e and motion to the 
same principle, affirming that reason sets the universe in 

Bmotion. Thales also, according to the traditional stories 
of him, appears to have conceived of the soul as a sort of 
kinetic principle, if it be true that he said the loadstone 18 
has a soul because it moves iron. Diogenes, however, 
and certain others say that the soul is air, in the belief 
that it is the finest element and the ultimate principle. 
It is for this reason, also, that the soul knows and 
produces motion. On the one hand, it knows by 
virtue of the fact that it is primary and other things 

L«re derivatives from it. On the other band, it is 

W&e principle of motion by virtue of its being the first 
element. Heraclitus, also, says the soul is the first 19 


principle, since it is fiery vapor from which every- 
tbing else is derived. It is also the most incorporeal of 
all the elements and is in constant Sux. We apprehend 
that which is moved by what is in motion, and he 
believed, as did most others, that the real world is in 

ao motion. Alcmaeon,^ too, appears to have held views of 
the soul very similar to these. For he saya the soul is 
immortal because it is like the Immortals, and this 
property of immortality belongs to it by virtue of its 
perpetual motion. Now, all divine things are in 
40s !• perpetual motion, — moou, sun, stars, and all the heavens. 

ai Certain cruder thinkers, like Hippo, asserted that the 
soul is water. They appear to have based their belief 
OD the nature of animal seed, which in all cases is moist. 
Hippo confutes those who say the soul is blood by the 
argumcat that the seed is not blood, and seed is the 

12 elemental aoul. Others, like Critias,'' regard the blood 
as the soul, on the supposition that the most charac- 
teristic attribute of the soul is sense-perception, and 
sense -perception is due to the blood. So all the 
elements, with the exception of earth, have received a 
vote. No one has represented earth as the principle of 
Boul, unless it were certain philosophers who regarded 
the soul as composed of all the elements, or as identical 

23 with them all. They all define the soul, one may say, 
in terms of three things: motion, sensation, and incor- 
' Alcmneon, phyBiciau of Crotona, who is usually olassified (unongat 
the FythngoresjiB. regnrded lelf-moTemenl as the ewentUI cburaoter- 
iatic of the Houl. By meanB of this power of aelf-movenient he appenn 
to have explained the continuity of organic life, in additioD to finding 
in it on argument for immortality. Yid. Siebeuli, Oesrhichii d. Psychol. 
Th. I. AUh. i. p. 91. 
* CritJBB, tho leader of the Tliirty Tyrants aud uncle of Plato. 


poreality, and each of these is referred back to the 
ultiinate elements. Therefore, with one exception,^ those 
who define the soul in terms of knowledge, make it an 
element or a derivative of the elements. For they say 
that we know like by like, and inasmuch as it is the 
soul that knows all things, it must consist of all the H 
elements. Those philosophers' who maintain there is 
only one cause and one element, regard the s«ul as a 
unit, like fire or air. On the other heuid, the philo- 
sophers who maintain that there are several elements, 
make the soul a plurality. Anaxagoras alone declares 
that the soul is affected by nothing and has nothing in 
common with anything else. But, if this is its nature, 25 
he did not explain, nor is it evident from his writings, 
how the soul is to acquire knowledge 6Uid virtue. The 
philosophers who include contraries amongst their first 
principles' regard the soul as composed of contraries. 
On the other hand, those who include in their principles 
only particular contraries,^ such as heat and cold or 
similar opposites, likewise regard the soul as one of these. 
And so there are some who take into consideration the 26 
derivation of the words, certain of them claiming that 
the soul is heat because the verb ' to live ' is derived from 
this,^ others claiming the soul is cold, because the name 
'soul' is derived from respiration and refrigeration. These, 
then, are the traditional views of the soul, and these 
are the grounds on which they have been advanced. 

^ Anaxagoras. ' The Ionian physiologers. 

' The Pythagoreans, who regarded the soul as a harmony of oontraries. 

^ Heraolitus, Empedocles, Hippo, and perhaps the pythagorizing 

"/.e. beoaose j^y (' to live ') is derived from ^ecir (* to seethe ') or ^1^ 
(' sonl ') from ^i^if (' refrigeration '). 



We must now proceed at once to the investigation of 
motion. For the view ^ that the soul is a self-moving 
4060 entity, and capable of imparting motion, may not only 
be a false theory of its essence, but it may even be an 
impossibility for motion to inhere in it at all. We have 
already said ^ that what imparts motion is not of neces- 

2 sity itself in motion. Everything that is moved is moved 
in one of two ways : it is moved either by some other 
thing or from a principle within itself. We speak of 
objects moved by some other thing when they are moved 
by being within a moving body, e,g, sailors. But sailors 
are not moved in the same sense as that in which a ship 
is moved. The one is moved in its own nature; the 
others are moved by being within a moving vessel. 

3 This is clear when applied to the parts of the body ; 
walking is a motion that is peculiar to the feet, but 
it is also a property of man, though it is not a 
property of sailors alt the moment in question. Now, 

^Criticism of the view of PUio. The paraphrast Themistins cites 

the Laws, Bk. 10, ed. Spengel. p. 26. Vid, Laws, 896, and Phaedr. 245, 


sPAy«. Bk. VH., Ch. iv. and v., 246 6-208 a. 





1 mo 

[ own 


luch as motion is employed in two senses, let 
investigate the eool, and ask whether it is self- 
moved or only participates in movement. Movements 
are of four kinds : movement in place, qualitative 4 
change, decay, and growth. The goal's movement, then, 
muBt be one, or several, or all of these. If it ie not 
moved accidentally, its motion must he a natural attri- 
bute. If this is true, then apace' must be an attribute, 
all of the aforesaid movements are spatial. If, then, 
le essential nature of the soul is self-movement, its 5 
movement will not be accidental, ;as in the case of the 
movement of a white object or of an object three cubits 
For what moves is body, of which these are only 
icates. Space, therefore, does not belong to them. 
it space is an attribute of the so\U, if the soul by its 6 
own nature participates in motion. Again, if the soul is 
moved by virtue of its own nature, it can also be moved 
ly external force. And if it can be moved by external 
ie, it can also be moved by virtue of its own nature. 
conditions hold in regard to rest ; for in the 
state into which an object is moved by nature, in this 

'The ugaments againat the PUtania doctrlaos are, briefly Banunar- 
ixed, u follovB : Motion csjuidI be the soul'a essential nature, (1) 
beonBe this would require that the aoul be ipatial ; (2) the soal mutt 
be moveable by external force ; (3) it muat be held in rest by extemml 
force, and these forced states of motion and rest are incouoeivablo ; 
(4) the oompoaition of the soul wtli be detenniued lif the character of 
it« moremeiits ; (5) it will experience the movements which it imparts, 
Uld as it effects apatial iDotiou, so it will e<perienoe spatial motion, 
and may oonsequeatly enter into the body oftttr having pused from it ; 
(6) if movement ia the displaoemeut of the object ia motion and the 
■onl'a esseDtial nature in movement, than motion would imply the soul's 
displacement out of its easeutial nature. Vid. Wallace's excellent 
note (Commentary ad loc.), parts of which I have osed in this coo- 



Btate it also rests by nature. Likewise when an object 
is moved hy external force into a certain state, it also 
rests in this state by force. It la not eaay to give even 
a conjectural explanation of the character of forced states 
of motion and rest in the soul. 

7 Agaui, if the soul's movement be upward, its composi- 
tion will be fire, and if downwards it will be earth, for 
these are the movements which are characteristic of these 
elements. The same reasoning holds good of the inter- 
mediate elements. Again, since the soul evidently seta 
the body in motion, it is reasonable that it also experi- 
ences those movements which it imparts. If this is true, 
it is also true conversely that the motion which the body 

406* experiences is experienced by the soul. Now, the body 

8 is moved in space. The soul should therefore change 
place as the body does, and either the entire soul, or 
certain of its parts, should change position. If this is 
possible, then it would also be possible for the soul to 
enter again into the body after it had once passed out. 
From this would follow the impossible conclusion that 
animals once dead can rise again. In regard to move- 
ment in the sense of accident, the soul could he set 
in movement by some external body, for an animal 

9 might e.i}. be pushed by external force. One most 
not, however, suppose that a thing which in its essential 
nature is self-moved, is moved by anything else save 
in an accidental sense; just as the absolute or 
final good cannot be the relative or secondary good. 
If the soul is moved at all, one would say that its 

10 motion is caused by the objects of sense more than by 
anything else. However, if the soul moves itself, it 



mast itself experience motioD, so that on the supposition 
that every movement is the displacement of the object 
in motion, in so far as it is moved, the soul most 
suffer displacement out of its essential nature, provided 
its self-motion is not merely accidental. But it is to 
its essential nature that motion belongs. There are n 
also some who, like Democritus, and in a spirit similar 
to that of the comedian Pbilippus, say that the soul 
moves the body' (in which the soul resides), just as it 
moves itself For Philippus tells us that Daedalus 
made his wooden statue of Aphrodite capable of move- 
ment by pouring quicksilver into it And Democritus ii 
says much the same thing when he tells us that the 
spherical atoms, which are never at rest, move the 
whole body by their pull and push. But the question 
we have to ask is whether these same particles produce 
rest also. It is difficult or quite impossible to say how 
they are to do this. In a word, it is not in this way that 13 
the soul seems to set the body in motion, but rather by 
some act of volition or thought. 

Similarly the Timacue^ explains on natural principles 
the soul's movement of the body : because it is self- 
moved, it also moves the body with which it ie 
intimately bound up. The Timat^m regards the soul as 14 
composed of the elements, and as divided into parts 
corresponding to harmonic numbers, in order that it may 
have an innate perception of harmony and possess iu its 
entirety harmonic movements. Timacits thus bent the 
straight line into a circle, which later he divided mto 
two circles joined at two points, and further subdivided 
■ I.e. b; mecboDicol action. ' Timaeiu, 34 A, 36 C. 



407 a the original circles into seven others, on the aupposition 

15 that the heavenly orbits correspond to the movements of 
the soul. Against this view one may say, in the first 
place, that it is incorrect to speak of the soul as a 
magnitude ; by the soui of the universe he evidently 
means some such thing as what we call reason. At any 
rate it cannot, of course, "be the sensitive or the appetitive 

16 soul, for their motion is not circular.^ But reason is one 
and continuous, as is also the process of thought. Now 
the process of thought consists of thoughts, and these in 
their succession form a numerical unity, though not a 
unity in the sense of magnitude. Neither is reason, 
therefore, continuous in this sense, but it is either 
indivisible or not continuous in the sense of magnitude. 
For how, indeed, is it to think, if it is magnitude ? 
Does it think in its entirety or by means of some one of 
its parts ? If it thinks by means of one of its parts, 
it must be either as a magnitude or as a point, if 

17 one can properly speak of a point being a part. Now, 
if it be as a point and the points are infinite in number, 
it is evident that it will never reach a conclusion ; i^ on 
the other hand, it be as a magnitude, it will think the 
same thing many times or an infinite number of times. 
But the fact seems to be that a thing is capable of being 
thought once for all. If, however, it is enough that the 
soul should have contact in any of its parts, why need it 

' The action of aenaatioii nod appetite in direct (i.f. thej are, a* Aris- 
totle conceivea them, directly from or to an object) and aiter the analogy 
of a straight line. The actiou of roasun, on the other hand, which 
interprets things in terms of its own forms and laws, and in thiahing 
ideas retnmi, in a sense, upon itaelf, ia analogous to circular movemeot. 
The analogy ii further evidenced by the continoity of its prooeaees. 
Cf. our expression to ' revolve ' a thing in thought. 


move in a circle or have any magmtude at all ? £ut if 
thought requires contact in a complete circle, what is the 
significaiice of contact in any part ? Again, how is the i8 
floul to think the divisible by means of the indivisible, 

_ or that which has no parta by means of that which has 
s 1 Reason, however, must be a circle of this sort. 
WOT thought is the movement of reason just as revolution 
is the movement of a circle. If, then, thought is a 
revolving movement, reason must be a circle of which 
thought is the revolving movement. And, more than 19 
this, reason must always think something, if circular 
motion is perpetual. Now, this cannot be true, for the 
thoughts which issue in conduct have certain limitations 
(they are all determined by an end), and speculative 
thoughts are determined by logical processes. Every 
gical process is either definition or demonstration. 
demonstrations proceed from a premise and have some 20 

■ibrm of termination in a syllogism or conclusion. And 
supposing they do not issue in a conclusion, still they do 
not turn back to the premise or starting-point, but 
coatiniially take a new middle and extreme term, and so 
proceed in a straight line, whereas circular motion turns 

-back to the starting-point. All definitions, too, are 21 
leterminate. Further, if rotation completes itself several 
mes, one will necessarily think the same thought several 
Again, thought seems more like rest and 
attention than Uke motion, and the same thing applies to 
the syllogism. More than this, whatever is difficult or 
intrary to nature cannot be pleasurable. Now, if motion 
b not an essential property of the soul, the soul must move 407 1 
poDtrary to its nature. And it must be painful for it to iz 



be united with the body from which it cannot &ee itself, 
and such a union is even to be avoided, if it be true that 
the reason is better off when separated from the body — a 
view commonly held and concurred in by many persona. 

»3 The cause, also, of the circular movement of the 
heavens is not clearly known. Circular movement is 
certainly not due to the essential nature of the soul, 
which moves in this way only accidentally, nor is it due 
to the body, for the motion of the latter is due to the 
souL On the other hand, this motion is not ascribed to 
the soul because of its being a better form of motion, 
and yet it is just for this reason that God must have 
endowed the soul with circular movement, firstly, because 

14 motion is better than rest, and secondly, circidar move- 
ment is better than any other kind Inasmuch as this 
inquiry belongs more properly to other branches of 
knowledge, let us dismiss it for the present. We may, 
however, note one contradiction found in this and most 
other theories of the soul. It consists in attaching the 
60ul to the body and placing it therein, without deter- 
mining why this should be the case, and how the body is 

35 related to the soul, although it would seem to be necessary 
to know this. For it is by virtue of this union that the 
one acta and the other is acted upon, that the one 
receives and the other imparts motion — correlations 
which are not found in things with merely accidental 

26 associations. These theories simply attempt to explain 

the nature of the soul, but add no explanation of the 

body as its receptacle, because they suppose (in the spirit 

of the Pythf^orean myths') that any soul can elot^ 

' More partiaalikcly in the myth of truiimigr&tion. 


ritself in any body. This cannot be tane, for every body 

NappeaiB to have a distinct form and character. Their 

doctrine is very much like saying that the carpenter's^ 

art clothes itself in flutes, whereas an art employs its 

own instrument, just as a soul employs its own body. 

1 The carpenter's art finds its physioal and material expression in a 
house bat not in a Ante ; farther, it nses not a Ante, but an axe, as its 
tooL A particnlar honse is the expression of a particular art or of 
particular ideas, just as a particular body is the expression of a definite 
and individual souL The soul is the entelechy and formative force of 
the body, and in it we look for the individuality and significance of the 
man. It is precisely on the relationship between soul and body that 
Aristotle lays especial stress in his definition of the former. 


There is another theory of the soul handed down from 
our predecessors, which to the minds of many persons 
is no less convincing than the theories already described. 
Account has been taken of it even in our popular 
treatises. This theory regards the soul as a sort of 
harmony.^ Harmony, say its advocates, is a mixture 
and combination of opposites. The body, too, is com- 

2 posed of opposites. Although it is true that harmony 
is a sort of relation in mixed parts or a combination 
of parts, we maintain that it is impossible for the soul 
to be either of these. Again, although motion is not an 
attribute of harmony, yet almost all of the philosophers 

408 a who hold the theory of harmony, I may say, ascribe 
motion to the soul. Another objection is that it is 
more fitting to apply the term harmony to conditions 
of health or to bodily qualities in general than to the 

3 souL This becomes most evident when one attempts to 
describe the effects and functions of the soul in terms 

^The reference is to the theory diacassed in the Phciedo by the 

gaests of Socrates, — Simmias and Cebes, pupils of the Pythagorean 

PhUoUns. Vid, Phaedo, 86 A ff. 



my ; for it is difficult to find any correspondence 

I them. Now, it we have two sorts of harmony 

mind when we use thia term, viz. harmony in the 

rimary sense, which means such composition of magni- 

kades in objects possessing motion and position that 

^ey fuse together and admit nothing further that is 

tomogeneous, and in the secondary seuse, a ratio in 

mixed elements, — we still object that in neither sense 4 

does harmony npply to the soiiJ. The composition of 

,the parts of the body can be readily examined. There 

: manifold combinations of the parte, which may be 

iffected in many waya Of what parts, then, is reason 

( combination and how is the combination effected ? 

md I raise the same question regarding the sensitive 

Ibd appetitive soul It is equally absurd to regard 5 

Boul as a ratio of mixture. The mixture of the 

ments, in the formation of Sesh and bone, is not in 

i ratio. If all the parts of the body are com- 

sed of mixed elements, and the ratio of this mixtui'e 

iBtitutes harmony and sou!, we have the absurd result 

lat we possess many souls distributed through the 

btire body. One might demand from Empedocles an 6 

IBwer to this question, for he says that every one of 

tse mixed elements is determined by a given ratio.' 

Bow tlie problem arises whether the sou] is this ratio 

I something else begotten in the members. Again, 

1 Love the cause of any chance mixture or only of a 

ouxture in which a fitted ratio is observed ? And is 

Love this ratio or something transcending the ratio 

and different ftom it ? This theory, then, involves such 7 

'Cf. Bnmat, Earli/ Greek PhUinophy, p. 227- 


difficulties as the foregoing. If the soul is difTeient 
from the mixture or combiDatiou, why in the world 13 
it that the soul is annihilated at the same moment as 
the existence of the flesh and the other parts of the 
living being ? Furthermore, if each part does not have 
a soul, on the ground that the soul is not the ratio of 
mixture, what is it that is destroyed when the soul 

8 leaves the body ? It is therefore clear from the fore- 
going that one cannot regard the soul as a harmony 
or its motion as circular. It is, however, possible for 
it to be moved accidentally and to move itself, as e.g. 
that in which it is may be moved, and this in turn 
may be moved by the soul. But spatial movement is 

9 otherwise impossible for the soul. One might with 
better reason raise objections against the movement of 

4oSi the soul, by regarding the following facta. We speak 
of the soul as feeling pleasure, pain, courage, fear, and 
anger, and as perceiving and thinking. Now all these 
processes are apparently movements, and on this ground 

10 one might suppose that the soul is moved. This, how- 
ever, is not necessarily so. For even if the feeling of 
pleasure or pain and the process of thinking be movements 
in the highest sense of the term, and each of these be 
a movement, it is possible that the movement is pro- 
duced by the soul just as the feeling of anger or fear 
is effected by a given movement of the heart and 
thinking by a movement either of this or of some other 
sort. Further, some of these movements ai* local, others 
are processes of change, but of what particular sort or 
how effected must be considered elsewhere. However, 

11 to speak of the soul as feeling anger is like speaking 


of the soul as weaving, or building a house. It is better 
not to speak of the soul as feeling pity, or as learning 
or thinking, but rather of man doing this through the 
souL We must not suppose, however, that this is so 12 
because there is movement in the soul, but that move- 
ment sometimes proceeds to the soul and sometimes from 
it, as e.g. in sensation movement proceeds from outside 
objects, in recollection the movement is from the soul 
to excitations or fixed impressions lingering in the sense- 
oigans. Now, reason appears to be an entity which is 
implanted in the soul and is incapable of being destroyed; 
for if it were perishable it would be destroyed by the 13 
decay of old age more than by anything else. As a 
matter of fact, the case is the same as that of the 
sense-oigans ; for if the old man could have the eye of 
a young man he would see as well as the latter. Old 
age, then, does not come because the soul has undergone 
some change, but the change is in the soul's organ, the 
body, as is the case in drunkenness and disease. 14 

Thought and contemplation are, it is true, weakened 
when some other internal organ is destroyed, but the 
principle itself is unaffected. The processes of discursive 
thought and the feeling of love or hate are not affections 
of the reason,^ but of that which has reason in it, in so 
far as it has it. Therefore, when this organism is 
destroyed there is no longer either memory or love. For 15 
these are not affections of the reason, but of that union 
of soul and body which has perished. Season, on the 
other hand, is somethmg of a divine nature, and is 

^ These proco—ce are not affeotiona of the eternal and separable Active 
Reason, but only of the body in so far as it possesses psychical life. 



imafTected by these changes. From these facts, therefore, 
it 18 clear that the soul is not in motion ; but if it is not 
in motion at all, it is clear that it is not self-moved. 
i6 By far the most unreasonable of the above-mentioned 
theories is the one which describes the soul as a self- 
moving number,* involving, as it does, impossibilities. 
In the 6rst place, it involvea impossibilities regarding its 
movement and especially regarding the notion of number. 
4090 For how are we to conceive of a monad, a thing which is 
without parts and without difl'erences, as in motion, and 
by what impulse and in what manner ? If it imparts 
motion and is moved, it necessarily contains differences. 

17 Again, since it is said that a line m motion generates a 
plane and a point generates a line, then the movements 
of monads will be lines, for a point is a monad which has 
position. And the number of the soul is, of course, 

18 somewhere, and has position. Again, if from a number 
one subtracts a number or a unit, the remainder will be 
a different number. But plants and many animals, when 

19 cut in two, live and appear to retain the same specific 
soul. It would also appear that there is no difference in 
speaking of monads and of small bodies. For if the 
atoms of Democritus are regarded as points, and quantity 
alone remains, there will still be in this quantitative 
element, as in everything continuous, a moving and a 

' The theory of Xeuocrates. 
harmony. XeDOcrstea appears 
the Boul 
Themutiua, ed. Speugel. p. 61). 

Thia theory is roally a, thoory of 
> have coDceived of the elements of 
ratio as lo produce a bttrmony (c£. 
The real oatare of this harmoDy is 

a the numerical ratio, and conaeqaently the eiumtial nature of the 
is fonnd in niimber. Tliis ia merely an applicatioD of the number 
theory of the Pythagoresna to the explanation of the aonl, to which, 
howerer, Xenocrateg adds tho important notion of self- movement. 



moved fftctor. And this consequence is due not to any 
difference inside, but merely to the fact that the elements 
I are quantitative. There must, tberefore, be something m 
I which Bets the monads in motion. But if the aoul is the 
f cause of animal movement, it will also be the cause of 
movement in the number ; the soul is therefore not at 
once the moving and the moved principle, but the 
moving principle alone. How then is it possible for the 31 
soul to be moved ? There must be some difference 
between it and other monads. But what difference can 
there be in monadic points, excepting a difference in 22 
position ? Therefore, even if the monads and points in 
bodies differ from each other, the monads will, neverthe- 
|le88, be in the same space as the points. For the monad 
F'WiU occupy the space of a pomt Now what is to 
prevent an infinite number from occupying the same 
space, if two can occupy the same apace ? This supposi- 
tion, however, is absurd ; for where the space occupied by 
. bodies is indivisible, the bodies themselves are indivisible. 13 
I But if the points in bodies are the number of the soul, 
or if the soul is the number generated out of corporeal 
points, why is it that not all bodies have a soul ? For, 
presumably, there are points, — even an infinite number 
Lof points, — in all bodies, Again, how is it possible 
I for souls to be separated and disintegrated from bodies,^ 
f if it be true that lines cannot be divided up into points.* 

ta and the PlatoQUts ■□ gojiera] mpported tbe doctruie of 

' tnunortality and the separability of the kiuI from the body. Ahstotla 

here mttempta to disprOTe the namlMr theory of the aoul by showing iti 

incompatibility with the tenet of separability, and the conaeqaeut inoon- 

eUtancy of the XenocratBan philosophy with itaelf. 

* Points ore not parts of lines, bnt only definite positiona or bono- 


The peculiar absurdity of the number-theory consists, as 
we said above, on the one hand in the fact that those who 
advance it maintain the same position as the supporters 
of the theory that the soul is a subtle body ; on the other 
hand, in their explaining the movement of the body by 
409^ means of the soul after the manner of Democritus. For 
if there is a soul in every body capable of sensation, 
there must be, on the supposition that the soul is body, 
necessarily two bodies in the same space. Again, those 
who maintain the numerical theory^ of the soul become 
involved in the absurdity either that there are many 
points in a single point, or that every body has a soul, 
unless they make a distinction between physical and 
2 psychical points. The consequence is that the animal is 
moved by number, in the same way in which we said 
Democritus explained its motion.^ For what is the 
difference whether we speak of the movement of small 

^By interpreting the number-theory of Xenocratee m self-moving 
monads, Aristotle rednoes it to similarity with the atomic theory of 
Demooritos, and applies the oritioisms of the latter to the former. 

*The animal is moved by psychical monads, jnst as in the theory of 
Democritus it is moved by psychical atoms (cf . De an, 4066 20). 




BBptierical bodies or of large monads or of monads at 
til ? For in either case the animal movement must 
■ be due to the motion of the monads. The above 3 
Kobjectiona and many similar ones may be raised against 
I the third' class of philosophers who combine motion and 
nnmber in their theory. This la not merely an impossible 
definition of the soul; it is even an impossible attributa 
This becomes evident if one tries to explain in terms of 4 
this motion* the feelings and functions of the soul, such 
as deductions, sense -perceptions, pleasure and pain, and 
L nmilar processes. It is not easy, as we said above,' in 
I terms of such a theory, to form even a conjecture of the 
I nature of these funcciona. Of the three* traditions! s 
I explanations of the soul, there is one which describes the 
Fsoul as the most mobile element because of its self- 
movement ; there is another which describes it as the 
most subtle or incorporeal element. The difficulties and 
contradictions involved in these two have been pretty 
I fully explained. There remains for us the consideration 
Ibf the theory of its composition from the elements. The 6 
IbouI is composed of the elements, certain philosophers 
I aay, in order that it may perceive and know all reality. 
[ But there are many difficulties which make this theory 
impoesible. Its advocates assame that like is known by 

' X«iiocrut«s uid the pythkgoriiitifj PUtoniBts. 

' Id Urms of number. ' Df an. 40y/i 32. 

'The eipl&iutioiui app&runtly reterrod to are : (t) that which reganla 
the Bonl aa a Eeli*iiioviug Dumber (Xeaoarates) ; (2) that which regards 
it M Domposed uf the 6iieat and moat mobile atomi (DemouHtus), or rif 
the aubtleat lubsionce (Aoaxagoru), or perhaps aa coDsiBting of Har- 
monj' (Plato) 1 |3) that which regards it aa compoaed of the element?. 
This third clais of theoriei laya chief weight on the aoitl aa an iDBtru- 
it of oognition. 

34 Aristotle's psychology dbanima 

like, thus making the soul and its object in a sense 

identical. But the soul knows not merely these elements ; 

it knows a great number, one would better say an infinite 

7 number, of other things, derivatives of the elements. Let 

it be granted that the soul knows and perceives the 

elements in every real thing ; by what means is it to 

know or perceive the concrete object, e,g, what is Grod, or 

man, or flesh, or bone, or any other similar composite 
410 a 

thing? For the elements are not combined in any 
haphazard way to form things, but in a fixed ratio 
and composition, as Empedocles himself says in r^ard 
to bone:^ 

*' Earth, the lovely, in her smelting pots, broad moulded, 
Obtained from sparkling Nestis * two parts of the eight ; 
Four from Vulcan's fire : so were white bones begotten." 

There is, therefore, no advantage in having the ele- 
ments in the soul unless the ratios and combinations are 
also to be found in it. Each element will know its 
similar counterpart, but it will not know bone or man 
imless these also are to be found in it. One need 
scarcely say that this is impossible. For who could be 
in doubt whether a stone or man were to be found in the 
soul ? The same holds true of the good ^ and the not- 
good, and equally of other instances. Again, inasmuch as 
the term 'Being' is employed in several meanings (it 

1 Vid. Burnet, Early Greek PhUoaophy, p. 227 ; Ritter and PreUer, 
Hist. PhiloB, Oraec, 8th ed., p. 148. 


' To Aristotle the good Is not an entity or element, and so is not 
explicable by the theory of Empedocles. The good is a relation, and 
consists in being a mean between two extremes, both of which (excess 
and defect) are evil. 


denotes e,g, the individual concrete thing, or quantity, or 
quality, or some other particular category), the question 
arises whether the soul is composed of all these cate- 
gories. It is supposed that there are no elements which 
are common to all the categories. Is the soul, then, lo 
composed only of the elements which fall under the 
category of substance? If so, how does it cognize the 
other elements ? Are we to say that there are elements 
and specific principles which belong to every category of 
existence, and that the soul is composed of these ? The 
soul will then be a quantity, a quality, and a substance. 
Now, it is impossible to form a substance or anything 
but a quantity out of elements of quantity. These and 
similar objections may be urged against the theory that n 
the soul is composed of all the elements. Again, it is 
absurd to say that like is unaffected by like, and yet 
maintain that like perceives like, and that we know like 
by like. At the same time these writers regard per- 
ception, as well as thinking and knowing, as a sort of 12 
affection and movement. The theory, as Empedocles^ 

I Empedocles starts with the psychological principle that like is 
known by like. Consequently, if objectiTe reality, which consists of 
the four elements (fire, earth, air, and water,) is to be known, then the 
knowing soul must be composed of the like elements. Aristotle's 
objections are as follows : (1) The soul not only knows the elements, bat 
a great many other things, for which the Empedoclean theory that 
*■ like is known by like * makes no provision. (2) It is of no value that 
the soul consist of the elements, unless in some way it be made to con- 
sist of the ratios and combinations of these elements. How, e.j/., can 
man or stone be known, for no one supposes that either of these is in 
the soul ? (3) In what category is the soul to be classed ? It cannot be 
regarded as all of them, for the different categories have no common 
elements, and if it is referred to one or the other of the ten categories, 
it wiU know only the objects that belong to this category, whUe it will 
be ignorant of the others. (4) Empedocles is further in the dUemma of 



states it, that things are severally cognized by means of 
somutic eleinentH and that like elements are cognized by 
like, is open to many objections and difficulties, as is 
proven by what we have just said. For it is plain that 
such elements in animal Jtodies as are composed merely of 
410* gross matter, like bones, sinews, and hair, do not perceive 
anything, not even objects like themselves. According to 
■3 the theory, however, they ought to perceive the like. 
Further, more ignorance than knowledge will attach to 
every element ; for it will know only one particular 
thing, while it will be ignorant of much, for its ignorance 
will extend u» everything else. And Empedocles is in 
the dilemma of making God the moat unintelligent of 
beings; for he alone is ignorant of one of the elements, 
viz., Strife, while mortals know them all, because they 

14 are foi-med from them all. There is, further, this general 
question to be raised : Why is it that all entities do not 
possess a soul, since everything is either an element or a 
derivative of one or several or all of the elements, and 

15 must, therefore, know one thuig or certain things or all 
things ? One might raise the further query : What is it 
that unities these elements into objects ? The elements 
are like a corporeal substrate, while it is the unifying 
principle, whatever that may be, that is the main thing. 
But there can be no superior principle to dominate thi- 
soul. This impossibility applies most of ail to reason. 
For reason is, witti good cause, called nature's Krst-born 

DMking Ciod the nuMt ignorsiit. uf Iminga, bcuauiH.' one {i-id, L'ebarweg. 
UemsH!, 8Ch eiL, Th. 1., p. 83) of Che elemenUI uOBioiuAl prindpleB— 
' Strila ' — U eioluded from his nature. (5) Agnin, why does not every 
oleinunt or combination of eletnents pouess a soul '! (6) The thitoTj of 
Kiiipedoclea provides no unifying pnuciplc. 


ruler, although these phUosophers regard the elements as 
the primary realities. All the philosophers who maintain i6 
the doctrine that the soul is composed of the elements 
because it knows and perceives realities, and those who 
describe it as the most mobile entity, fall into the error 
of not referring to the soul in its entirety. For not 
every sentient creature is capable of movement^ Certain 
animals are observed to be stationary in place. And yet 
this seems to be the only form of movement that could 
be meant when one says 'the soul moves the animal.' 
A similar objection may also be urged against those who 17 
describe the soul and the sentient principle as composed 
of the elements, viz., that plants evidently live without 
participation in movement or sensation, while many 
animals are not endowed with thought But even if 
one were to make a concession and r^ard reason as a 
part of the soul, in a sense similar to that in which the 
perceptive faculties are parts of the soul, still even then 
one would not be taking every form of soul into con- 
sideration, nor the whole of any particular soul. And 
this is just what happens in the account of the soul given 18 
us in the Orphic verses, as we call them.^ For there we 
are told that the soul enters from the universe into 
individuals as they breathe, and that it is carried by the 
air. But this is impossible in the case of plants and 
also in the case of certain animals; because not all of 4ii<' 
them breathe — a fact which the supporters of this view 19 

^ This objection appears to apply not to Empedocles, bat to Demo- 
critns and Xenoorates. Motion cannot belong to the essential nature of 
soul, for certain sentient creatures are stable and incapable of motion. 

'Aristotle evidently considered the Orphic origin of these early 
Cosmogonies as a doubtful tradition. 

38 ARISTOTLF/s PSYCH0L0(4Y de anima 

have overlooked. Even if we admit that the soul must 
be composed of the elements, it is not necessary that it 
be composed of all of them; for either member of two 
contraries is competent to discern both itself and its 

20 opposite. For example, by the concept of the straight 
we discern both the straight and the crooked ; the rule is 
the test for both, while the crooked is not a test either of 
itself or of the straight. 

Certain philosophers^ maintain that the soul is diffused 
throughout the universe, which may account for Thales'* 
thinking that all things are full of gods. This view is also 

21 attended by certain difficulties. Why is it that the soul 
which is in the air or in the fire does not generate an 
animal, while such generation takes place in compound 
bodies, although they regard that which is contained in 
the former elements as superior to that which is con- 
tained in compound bodies. One might also ask the 
question : Why is it that the soul contained in the air is 
better and more imperishable than that which is found 
in the animal body ? There is a two-fold objection to 

22 this theory : it involves an inconsistency and a paralogism. 
To speak of fire or air as animal is paralogistic ; while 
not to call them animal, if they have a soul, is incon- 
sistent. They appear to think there is soul in these 

23 elements on the ground that the whole is homogeneous 
with its parts. The result is, they must say that the 

^ The reference here may be to the theories advanced in the 7Vmaeu« 
(SOB, 34 B; cf. Barth^leniy-StHilaire, PnychoU (TAriatoU, p. 156, 
and Themistias Comment, ad loc.), or to the theories of Heraclitos 
or Empedocles or Diogenes of ApoUonia. The theory of panpsychism 
is best represented by the post- Aristotelian Stoics. 

> Vid. Burnet, Barly Greek PhUoaophy, p. 42. 


soul is homogeneous with its parts, if it be true that 
animals become endowed with soul by taking into them- 
selves something from their environment. If, however, 
the difiFused air is homogeneous, and the soul consists of 
heterogeneous parts, it is evident that some of its parts 
and not others will be contained in the air. The 24 
consequence is that the soul must either consist of like 
parts or not be found in every element of the uni- 

From the aforesaid it is evident that knowledge does 
not belong to the soul in virtue of its composition out of 
the elements, neither is it right or true to say that it 
is moved. But inasmuch as cognition, sense-perception, 25 
and opinion, as well as appetite, volition, and desire in 
general are functions of the soul, and inasmuch as 
locomotion in animals is effected by the soul, and it is 
also by virtue of the soul that animals grow, reach their 
prime, and decay, the question arises whether each of these 
functions is to be ascribed to the entire soul. In other 411!^ 
words, is it by means of the entire soul that we think, 
perceive, and are moved, and perform and undergo every 
other process, or do we perform each different function by 
means of a different part ? Again, we may ask whether 26 
the principle of life is found in each one of these parts 
or in several or in all of them. Or is something other 
than the soul ^ the cause of life ? It is true that some 
writers maintain the divisibility of the soul and that one 
part exercises thought and another part exercises desire. 

^According to Ariatotle, life is one of the peychical fcmotioiui, 
although the most elementary of all of them, and is a prerequisite to 
all other forms of psyohical activity. 


27 If the soul is really divided in ilB nature, what is it that 
holds it together ? It is certainly not the body ; for, on 
the contrary, one suppoaes that the soul holds the body 
together. At any rate, when the soul departs the body 
is dissolved and disintegrated. If, therefore, it is some- 
thing other than the body that makes the soul an unit 
this would assuredly be the soul itself, and we shall 
be obliged to inquire again whether that unifying 
principle is itself an unit or is composed of several parte. 

a8 If it is an unit, why should we not say at once that the 
soul is an unit ? But if it is divisible, reason will again 
ask what that principle is which holds it together, and so 
the process will go on drf infinitum.. In regard to the 
parts of the soul, one might inquire concerning the power 

19 which each of them has in the body. For if it is the 
soul as a whole that binds the entire body together, it 
would be fair to suppose that each part of the soul is the 
binding principle for some part of the body. This, how- 
ever, appears to be impossible. It is hard even to fancy 
what sort of part the reason will bind or in what way, 

30 It is observed also that plants and certain insects, when 
divided, continue to live, because the sections possess 
souls, which are specifically, although not numerically, 
the same, Each part retains the power of sensation 
and locomotion for some time, and there is nothing 
strange in the fact thaE it does not continue to live, 

ji because it has no organ for the maintenance of its nature. 
Nevertheless the parts of the soul are all found in every 
one of these bodily divisions, and they are of like kind 
with each other and with the entire soul ; of like kind 
with each other because they are mutually inseparable; 


of like kind with the entire soul because it is divided 
into these as parts. Again, the fundamental principle of 
life in plants appears to be a kind of soul, and this is the 
only principle which animals and plants have in common. 
The principle of life can exist apart from sensation, but 
no sentient thing can exist without life. 



412 a Lbt the foregoing suffice aa a discussion of the traditional 
theories of the soul ; and now let us resume our subject 
from the start, and attempt to determine the nature of 
2 the soul and its most general definition. One class of 
realities we call 'substance/ This 'substance' may be re- 
garded on the one hand as matter, which in itself is no 
definite thing; on the other hand, as form and idea, in 
terms of which definite individuality is ascribed to a 
thing. A third meaning of substance is the composite 
of matter and form. Matter is potentiality; form is 
actuality or realization.^ The latter may be looked at 

^ The notions here under difcuasion belong to the most fundamental 
with which the philoeophy of Aristotle operates. The soul is character- 
ized by several terms, chief of which are form and enUlechy, Every 
individual or ' substantial ' thing is a composite of form and matter. 
Form is that which gives a thing its character or significance. It is 
form, therefore, that is the object of knowledge. Becoming consists in 
the process of matter assuming a definite form. Matter, consequently, 
represents the potentiality of a thing, and form its actuality. Viewed 
from the standpoint of causation or process, these two notions constitute 
the material and formal causes ; in other words, matter is the oondition 
ewe qvM nont while the form is conceptual, efficient, and final cause. 



[ two ways, either as complete realization, — comparable 
with perfected knowledge, or as realization in process, — 
comparable with the activity of contemplatioD. The 3 
notion of substance appears to be most generally employed 
in the sense of body, and particularly of physical body : 
for ibis is the source of all other bodies. Some physical 
bodies have, and others have not, life. By life we under- 
stand an inherent principle of nutrition, growth, and 
decay. So that every iiatuml body endowed with life 
would be substance, and substance in this composite sense. 4 
The body, therefore, would not be soul, since body is of 

TheBe faDdsmmMl temu hi AiiaCotle'a mebLphysUas ftre Applied by bini 
to the eiiplanation of the bouI. Mui is first of all an organic whole, the 
living force in which ia the soul, while the body U tlie loul'* organ. 
Soul is that which dilTerentiates a living from an inanimate thinj;, 
{De OH. AlZa 33), and life HigBilies a process or a form of motion. Life 
implies, further, an active and a passive element; in other words, a 
moving principle and a thinf{ moved, which in Aristotle's terminology 
are form and matter. Form here ia equivalent to the moving or 
efficient onse. It ia the enei'gy or life that determines the growth of a 
pai'ticular body, or its trauaiiion, in Aristotolian language, from 
potentiality to actuality. Every living thing, then, is a compotite of 
form and matter, or loul and body, !□ so far as the form is the 
perfected end or final cause, in so far Aristotle describes the sunt as the 
entelechy of a natural orgonie body. In so far as it is an efficient power 
or moving cause, he describes t)ie soul as tbe actnality or actualization 
(an inodeqaate translation of tripytia). It is only in the "soul that 
liotly attains its trae reality " (Wallace, Introd, p. xudi.). Soul is the 
realiKation nf the body, apart fi'om which the body is only fomdeat, 
undeveloped, potential matter. Ent«lechy {etTiMx"") feana tbe 
finished state of a thing (Fhi/i. SiBa 24) or a stale in which a thing's 
potentiality finds ita complete development. Actualization (ri'/frYcia}, 
on the other hand, means the active prci^ss by which the potential 
thing poKseH over into the completed stnte or it is the completed 
state in prmiesa. Entelechy is, therefore, more ultimate than 
aotualizalion {M/rytta), stlhough Aristotia frequently uses the terms 
synonymously. On the term Mpytta, vid. Grant's Ariitoi/t'K Ethkn, 
'. 4th ed., and Trend elentmrg'a Ari'lMlr'' l)t anima. 


pp. S 

44 Aristotle's psychology dbakima 

such nature that life is au attribute of it For body is 
not predicated of something else, but is rather itself sub- 
strate and matter. The soul must, then, be substance^ 
in this sense: it is the form of a natural body 
endowed ¥ritii the capacity of life. In this meaning 

5 substance is the completed realization. Soul, therefore, 
will be the completed realization of a body such as 
described. Complete realization is employed in two 
senses.^ In the one sense it is comparable with per- 
fected knowledge; in another, it is comparable with the 
active process of contemplation. It is evident that we 
mean by it here that realization which corresponds to 
perfected knowledge. Now, both waking and sleeping 
are included in the soul's existence : waking corresponds 
to active contemplation; sleep to attained and inactive 
knowledge. In a given case science is earlier in origin' 

6 than observation. Soul, then, is the first^ entelechy 

^ SubstaDCd i8 employed by Aristotle in three senses : (1) matter ; (2) 
form ; (3) the composite of matter and form or an individual thing. Cf. 
Zeller's AristoUe, Engl. tr. Vol. I. pp. 374 ff. ; Qrote's ArintoUe, p. 454. 

^ These two senses are described by Aristotle in the terms entelechy 
and actualization (^i'^f>7eta), the former of which corresponds to * per- 
fected knowledge ' and the latter to the process or activity of ' contem- 

^ In the sense of being a dormant possession, or a potentiality which 
subsequent activity presupposes. 

^The 'first' entelechy is variously explained by the different oom. 
mentators from Simplicius down. The notion of * first ' appears to refer 
to the distinction made in the previous Note. There is a primary and 
secondary substance {oC(rla)t the former of which refers to the individual, 
and the latter to the genera ; there is a primary matter (irpc^ (^17, 
Metaph, 1049a 25), which signifies matter absolutely formless ; there b, 
further, a primary soul (xptimi ^t/x^, J)e an, 416& 22), which is the 
most fundamental or primary form of soul, viz., the nutritive function ; 
and similarly there is a first entelechy [rfHirrri ^rreX^x^ia), which is the 
primary or most fundamental form of psychical life. It is primary or 



^^ and 

of a Datural bfxly endowed with the capacity of life. 
Sach a body one would deecribe as organic. The parte 
of plants are also on^ans, although quite simple in ciiar- 413 h 
acter, e.ij. the leaf is the covering of the pericarp, and 
the pericarp is covering of the fruit ; the roots are 
analogous to mouths, both being channels of nutrition. ^ 
If then we were obliged to give a general description 
applicable to all soul or life, we should say that it is the 
first entelechy of a natural organic body. It ia therefore 
unnecessary to ask whether body and soul are one, as one 
should not ask whether the wax and the figure are one, 
or, in general, whether the matter of a particular thing 
and the thing composed of it are one. For although 

ity and being are predicated in several senses, their 

iper sense is that of perfect realization. 

We have now given a general <lefinition of the soul, s 
We have defined it ss an entity which realizes an idea. 
It is the essential notion which we ascribe to a body 
of a given kind. As an illustration, suppose that an 
instrument, t.g. an axe, were a natural body. Here the 
notion of axe constitutes its essential nature or reality, 
and this would be its soul. Were this taken away it 
would no longer be an axe, except in the sense of a 
luym. It is in reality, however, merely an axe, 9 
of a body of this sort soul is not the notional 

lint ID the Beu» of being nenrcat to mere potentiality, uid in the ordei 
of development Btuiila next above body. It ia abo first in Iwing a pre. 
requisite to all further dBvelopment. Tho • firat entelechy of a body ' ia, 
ooDieqaeiitiy, the lirsC maDifestation of life which an orgajiUm diBptaya. 
It cocreaponda to dormant knowledge or merely poasesaed aoicnce. 
which ii potentiality \fi6ni)u\, f(ii) compared with the active employ- 
ment of Bciencs (A^frycio), and aa potentitiUty, it ia prior to the Utter. 



\\%X. Zeller'a vjrivofe, Kngl. Ir. Vol. II. ] 

el. I 


essence and the idea, but soul applies only to a natural 
body of a given kind, viz. a body whose principle of 
movement and rest is in itself.^ The principle expressed 
here should be observed in its application to par- 
ticular parts of the body. For if the eye were an 

10 animal, vision would be its soul, i.e, vision is the notional 
essence of the eye. The eye, however, is the matter of 
vision, and if the vision be wanting the eye is no longer 
an eye, save in the meaning of a homonym, as a stone 
eye or a painted eye. What applies here to a particular 
member, must also apply to the entire living body; for 
as the particular sensation is related to the particular 
organ of sense, so is the whole of sensation related to 
the entire sensitive organism, in so far as it has sensa- 

11 tion. 'Potentiality of life' does not refer to a thing 
which has become dispossessed of soul, but to that which 
possesses it. Seed and fruit are potentially living bodies. 
As cutting is the realization of the axe, and vision is 
the realization of the eye, so is the waking state the 
realization of the living body; and as vjftion and capflnity 

413 a are related to the organ, so is the soul related to the 
body. Body is the potential substrate. But as vision 
and pupil on the one hand constitute the eye, so soul 
and body in the other case constitute the living animal. 

12 It is, therefore, clear that the soul is not separable from 
the body; and the same holds good of particular parts 
of the soul, if its nature admits of division, for in some 
cases the soul is the realization of these very parts; 

' The meaning is that if an axe were a body with an inherent principle 
of movement, or in other words an animate body, then the notion of 
axe or axehood would oonatitnte its souL The soul, then, is the 
' notional essence,' to use an Aristotelian phrase, of a living body. 


not but that there are certain other parts where nothing 
forbids their possible separation, because they are not 
realizations of any bodily nature.^ And yet it is un- 
certain whether the soul as realization of the body is 
separable from it in a sense analogous to the separability 
of sailor ^ and boat Let this suffice as a definition and 
outline sketch of the soul. 

^ The reference is to the Active Reaaon. 

'As the sailor is the directing and animating principle, as it were, 
of a boat and is able to leave it at wiU. 


Inasmuch as the certain and the conceptually more 
knowable is derived from what is uncertain,^ but sensibly 
more apparent, we must resume the investigation of the 
soul from this standpoint For it is necessary that the 
definition show not merely what a thing is, as most 
definitions do, but it must also contain and exhibit the 

2 cause of its being what it is. In reality, the terms of 
definitions are ordinarily stated in the form of con- 
clusions. What, exf, is the definition of squaring ? The 
reply is that squaring is the conversion of a figure of 
unequal sides into a right-angled equilateral figure equal 
to the former. Such a definition is the expression of 
a conclusion. But to define squaring as the discovery 

3 of a mean proportional line is to define the thing in 

^The only certain and scientific knowledge to Aristotle ia that of 
concepts or aniversals, although this is in a way derived from sensible 
data. Aristotle is not, however, a pnre Empiricist. Sense-per- 
ception itself is not a passive reception of external impressions; 
these famish rather only the occasion of a given psychical activity, 
and rational thought is in still higher degree a matter of subjective 
initiation. He rejects, however, the Platonic theory of reminiscence 
and aU other theories which assume the possession of a body of innate 



H^^f seni 


terms of its cause.' Resuming our inquiry, we say, 
therefore, that the animate is distinguished from the 
inanimate by the principle of Hfe. But inasmuch as life 
is predicated in several senses, e.g. in the sense of r 
sensation, local movement and rest, and furthermore 
movement in the sense of nutrition, decay, and growth ;' 4 

' The one definitioD describea the retult accomplUbed, atid the other 
the meani uid method of ita accamplishment. Although ArUtotte haa 
great veneration for facts, to a degree remarkable in Greek philoaophj, 
he conBtantty lays emphasiB on the Buperior aigniiica 

'Aristotle's vien of aonl or t!hc > vit&l principle' {neither tranalation 
givea qaite an adequate idea of the meaning of fvx^, cf. Introduction, 
Chap, i.) ii different [roni that of Stahl and the Montpellier School of 
Animiett. Tbo latter regard the mind aa the Houroo of all vital phe- 
nomeDa, whereas Ariatotle reg&rda life as the source of mind, or rather, 
mind as only one of aeveral forniB of life. The distinction between the 
two views IB made greater by Lewes lAriniotle, p. 223] thao the facts 
justify, he having, as he tuppoBes, made the diacoTery of this 
distinctioii. In reality Aristotle characterizes life as a psychical 
activity, thoagh not necessarily intelbgeot. The organic a 
plants is psychical, although they have no sensation. Aristotle used 
life in a wider meaning than we do ; with him it included reason 
and sensation, aa amongst the vital activities of organized beiogB. 
These combined activities coasbtated ' soul ' in distinction from the 
material substrata or body, in which they are maoifeBted. Stabl 
(I66U-1T34), whose theory of the soul grew out of his physiological 
studies and was a reaction ag&inst mechanical and chemical theories, 
rejects the Aristotelian distinction oF a vegetative and nutritive sonl, 
and refers all these functions to rational thought. The three forms of 
vital movement for Stabl are the circulation of the blood, aecretion, and 
excretion, all of which Aristotle includes amongst the activities oE 
nutrition, save that the circulation of the blood takes the form of 
movemeut from the heart to the extremities aud back again. Stahl says 
the cause of this is the mind ; .Arisiotle says it is the nutritive soul or 
the lowest form of vital activity. Both are vitaliste io the repndiation 
of a mechauicol explanation of life ; both are animists in referring the 
phenomena of life to tbe soul. They differ to that Stahl makes all 
these activities rational, while Aristotle regards as rational only specific 
n higher animal life. Cf. Lemoiue, Le vUaiimie tt fanimisme 

<it Stahl, pp. 33 S. 





if aDy one of these is discerned in a thing we say that 
it has life. Alt plants, therefore, are supposed to have 
life ; for evidently they have within them a potency 
ftsd principle whereby they experience growth and decay 
in opposite processes. For their growth is not merely 
upwards or downwards, but in both these directions 
alike and in every point where nutrition takes place, 
and they continue to live as long as they are capable of 

5 nutrition. Now this faculty of nutrition is separable 
from the other forms of life, but the other forms cannot 
exist in perishable creatures apart from this principle 
of nutrition. This is made clear in the instance of 
plants ; for they have no other capacity of soul (or life) 

Ii3« than this nutritive one. Owing to this fundamental 

6 principle of nourishment, therefore, life is found in all 
animated living things, but the primary mark which 
distinguishes an animal from other forms of life is the 
possesaioTi of sensation. For even those creatures which 
are incapable of locomotion or change of place, but 
which possess sensation, are called animals and are 
not merely said to live. Touch is the primary form 

7 of sensation and is found in all animals. But as the 
nutritive faculty is separable from touch and sensation 
in general, so touch can exist apart from the other forms 
of sensation. Bj the nutritive power we understand 
that part of the soul in which plants share; and by 
the sensation of touch we mean that capacity which 
all animals possess. We shall later on give the ex- 
planation of these phenomena. 

a For the present let it suffice that the soul is the 
causal principle of tlie aforesaid phenomena, and is 



I defined in terms of thexii, I mean, in lerms of nutrition, 

I sensation, reason, motion. To the question whether each 

l^of these forms of life is a soul or a part of the soul; 

, if a part, whether in the sense that the part is 

' only notionally separable or really separable in space, — 

the reply ie in some respects easy and in others 

difficult. For in the case of plants, some of them appear 9 

L to live when they are divided up and the parts are 

I Beparated from each other, indicating that there is in 

I web of these plants in actuality an unitary soul, but in 

I potentiality several souls. And we observe the same 

I thing taking place in different varieties of soul, as €.g. in 

I the case of insects which have been dismembered. Here 

I «ach part is capable of ueusation and locomotion, but if it 

s capable of sensation it is also capable of imagination 

I and impulse. For where there is sen.sation, there is also 

I pleasure and pain, and where there ia pleasure and pain 

there is necessarily also desire. Now in regard to roawn ic 

and the speculative faculty, we have as yet no certain 

evidence, but it seems to be a generically distinct type of 

soul and it alone is capable of existing in a state of 

separation from the body, as the eternal is separable from 

the mortal' The remaining parts of the soul, however, n 

are from the foregoing considerations evidently not 

separable, as some assert* But that they are notionally 

'Amnngat the uncertftin and wavering Btittementa of Ariitotla 
regarding the aepanbilily of th« rational Boal and ita uaniortkUty, this 
ia one of the most eipUcit paaiagei, 

* The reference appears to be to PUto who regarded the >oul u con- 

•Uling of three diatiuct fiKuUiei. — the rational, spirited, nod appetitive 

IReptib. 440 A, B, Timaeut, 69. 70). which were litoated in different 

parts of the body,— reason in the head, tlie spirited elemeot ID the 

I tborui, and the cuncupiacent facDltiea in the lower body. 




separable, is clear; for if perceiving is dietinct from 
opining, the faculty of sensation or perception is dis- 
tinct from that whereby we opine, and each of these is 
in turn distinct from the faculties above mentioned. 
13 Furthermore, all of these are found in some animals, 
while only certain of them are found in others, and in 
still others only a single one (and this is the cause of dis- 
414" tiQCtioDs amongst animals). The reason for this must be 
investigated hereafter. A parallel instance is found in 
regard to sensation ; some animals possess all the faculties 
of sense, others ouly certain of them, and still others only 
the single most fundamental one, viz. touch. 

13 The principle by which we live and have sensation, 
then, is employed in a twofold sense. Similarly, we 
employ the principle by which we know in a twofold 
sense, viz. science and the knowing mind (for we say we 
know by means of each of these), and in a like manner 
the principle by virtue of which we are healthy is in one 

14 sense health itself, and in another sense a part of the 
body or the whole of it. In these cases knowledge and 
health constitute the form, notion, idea, and, as it were, 
the realization of a potential subject, — the one of a 
knowing subject and the other of a healthy one, 
(realization is supposed to attach to that which has 
power to effect changes and is found in a passive and 
recipient subject). The soul is that principle by which 
in an ultimate sense we live and feel and think ; so that 
it is a sort of idea and form, not matter and substrate. 

15 Now, substance is employed, as we have said, in a three- 
fold meaning, viz. as form, as matter, and as a composite 
of these two. Amongst these meanings of substance 


matter signifies potentiality; form signifies actuality or 
complete realization. Inasmuch as it is the composite 
which is the animate creature, body cannot be regarded 
as the complete realization of the soul, but the soul is the 
realization of a given body. The conjecture, therefore, i6 
appears well founded that the soul does not exist apart 
from a body nor is it a particular body. The soul is not 
itself body, but it is a certain aspect of body, and is 
consequently found in a body, and furthermore in a body 
of such and such a kind. It is not to be regarded as it 
was amongst our predecessors who thought that it is 
introduced into body without prior determination of the 
particular sort of body, although no casual subject 
appears capable of undergoing any casual or haphazard 17 
effect.^ This same result is also reached by an analysis 
of the notion itself; for complete realization in every 
instance is naturally found in a definite potentiality and in 
an appropriate matter. From this it is evident that the 
soul is a kind of realization and expressed idea of a 
determinate potentiality. 

^Trendelenburg thinks the Fythagoreana are meent here, owing to 
their doctrine of tranamigration of aonls. The doctrine that one soul 
can dothe itself in different sorts of bodies is ms impossible ms that one 
craft can nse the tools of other crafts indifferently. Cf. De on. 4076 22; 
. also note, p. 26. 


In some creatures, as we have said, all of the above 
mentioned psychic powers are found, in others certain of 
them, and in still others only one. By powers we mean 
here the power of nutrition, of appetite, of sensation, 
of movement in space, and of rational thought. In 
plants, only the nutritive power is found; in other 
414 ^ creatures the power of sensation is added. If sensation 

2 is added, impulse or appetite is also implied. For 
appetite includes desire and impulse and wish. All 
animals have at least one sense — touch ; and to whatever 

\ creature sensation is given, to it are also given pleasure 

\ and pain, and objects appear to be pleasant or painful. 

y^reatures which distinguish these, possess also desire ; for 

desire is an impulse towards what is pleasant. Further, 

3 animals possess a sense for food, and this is the 
sense of touch ; for all animals are nourished by means 
of the dry and moist, the warm and cold, and it is 
touch which apprehends these. It is only incideutaUy 
that animals discern food through other sensible 
qualities; neither sound nor colour nor smell con- 
tributes at all to food. Flavour, however, is one of the 



baptic qualities.' Hunger and thirst are desires ; hunger 4 

is a desire of the dry and warm ; thirst a desire of 

the cool and moist, and flavour is a sort of seasoning 

in these ohjects. We must explain these eubjccta 

minutely hereafter ; for the present let the statement 

LsnfBce, that amongst animals where we find touch 

I we find appetite also. The Bubject of imagination 

' in animals is uncertain and must be investigated later. 

In addition to these attributes we find amongst some 5 

animals the power of local movement and in others we 

the power of understanding and reason, as in man 

I and in other creatures that are, if there be such, similar or 

I superior to man. It is evident that a single de&nition 

I can be applied to soul in the same way as a single 

' definition can be applied to figure. As in the latter case, 

there is no figure beyond that of the triangle and its 

derivations, so in the former case there is no soul beyond 

those enumerated. A common definition might also be 6 

■ applied to figures which would fit them all and be 

I peculiar to no particular figure. The same holds good in 

I the case of the above mentioned types of soul It is, 

therefore, absurd,^ both in these instances and in others, to 

search for a common definition which shall not apply to 

any individual real thing nor to any peculiar and irre- 7 

'Touch in tho moat fuDdametit&l of all the senses, and taste is depen- 
dent upon it. These two are esaentill to the preservation of animal life. 
No animal csn be without touch and noChing that is without it con be an 
•uimal. As the primary form of Bensation, it ia the lowest diOerential 
mark of animal life, distinguish iag the animal from the vegetable. 

'Aristotle is referring to an absurdity not fully expressed here. 

The meaning appear* to be that, although such a general definition 

might be framed, it would be void of nay helpful content or significanoe, 

I not being applicable to any particalar form of reality. 


ducible species, thereby aeglecting the particular meaning 
in the general. The facts touching the soul are parallel 
to this case of figure ; for both in Bgures and in animate 
creatures, the prior' always exists potentially in the later, 
f.g. the triangle is contained potentially in the square and 
the nutritive power in that of aenaation. We must, there- 
fore, investigate the nature of the soul in particular things, 

8 e.g. in a plant, a man, or a lower animal. And we must 
'5" consider the cause of their order of succession. The 

sensitive soul, for example, presupposes the nutritive, but 
in the case of plants the nutritive exists apart from the 
sensitive. Again, the sense of touch is presupposed by 
all the other senses, but touch exists apart from them 
and does not presuppose them. Many animals have no 

9 sense of sight, hearing, or smell. Some that are capable 
of sensation have also power of local movement, others 
have not; finally the smallest number poaeesa the power 
of reason and understanding. Mortal creatures who 
possess the power of reason, possess all the other psychic 
faculties, but those whicl have each of these others do 
not all have the power of reason, and certain of them do 
not even possess imagination,^ while still others live by 
this alone. At another time we shall give an account of 
the speculative reason. It is evident, however, that this 
account touching each particular form of soul is also the 
most fitting description of the soul in general. 

' The logically prior is meant . 

' ImagiaatioQ U of two sorts (i^arTaffia adrPitrdi vid #arra<rla ^ouXfin-iii) 
fl \»viffTijii4)i the one of which is the power of rept'oducing images of seiue 
or of reviving epent seiuatiouB ; the other is the power of construotiug 
the images that ftccompany thought, always, however, out of elements 
ultimately drawn from sensation. Cf. Introduction, On Imaginalitm. 


If one intends to make an investigation of the faculties of 
the soul, it is necessary first to inquire into their several 
natures, and then by the same method to inquire further 
into other related problems. If, then, one is obliged to 
describe the nature of each several faculty, e,g. the 
nature of the faculty of reason, of sense-perception, or of 
nutrition, one must first be able to say what thinking 
and sense-perception mean. For the activities and pro- 
cesses are notionally prior to the fiEiculties to which they 
belong . If this is true, we must further observe the 2 
objects of the activities before the activities themselves, 
and we should for the same reason first determine our 
position r^arding these objects, e.g. regarding food, the 
sensible, and the intelligible. First, then, we must speak 
of food and generation. For the nutritive power is found 
in all living things, and is the primary and most uni- 
versal faculty of soul, by virtue of which all creatures 3 
possess life. Its functions are to procreate, and to assimi- 
late_food. In afi animals that are perfect and not 
abnormal, or that are not spontaneously generated, it is the 

most natural function to b^et another being similar to 



itseJf, an animal to beget aoother animal, a plant another 

plant, in order that they attain, as far as possible, the 

415* immortal and divine'; for this is what every creature 

4 aims at, and this is the final cause of every creatore's 
natural life. We understand by final cause two things : 
the purpose aimed at, and the person who ia served by 
the purpose.^ Since it is impossible for an individual to 
partake of the iounortal and divine in its own contumons 
life, because no perishable creature continues aelf-identical 
and numerically one, it partakes therefore of the immortal 
in that way in which it is able to share it, one thing in a 
higher degree and another in a lower; it does not itself 
abide, but only a similar self abides ; in its continuity it 

_ is not numerically, but only specifically, one. 
^^C 5 The soul is the cause and principle of a living body. 
These terms are used in several senses. Corresponding 
to these differences, the soul is referred to as cause in 
three distinct meanings ; for it is cause in the sense of 
the source of movement, of final cause, and as the real 

6 substance of animate bodies,^ That it is a cause in the 
sense of real substance is evident, for real substance is in 
every case the cause of being, and the being of animals is 
their life, and soul is the cause and principle of life. 
Furthermore, it is the complete realization that gives ns 
the real significance of a potential being. Soul is also 

' The only immortAlity possible far ODJnials aneadowed with Active 
Rmboq ia that of the perpetnatloD of their speciea through propags- 

' For example, the end or pnrpoae of e. lamp m»y be said to be either 
la) to give light, or {b} to aervE the wants of the person who employs 
the light. 

' In other word^, aoal is used iu the meaniiigR of effioiout, final, aod 

formal cause. 


^^^ tonoi 

i: pro* 

^^^ ascri 

^^^ leape 

1 are 



ideally cause in the senee of final cauae. For nature, 
, acta with purpose, and this purpose is its end. 
animals the soul ia, by virtue of its nature, a principle 7 
to this. For the soul uses all natural bodies as^ 
instruments, the bodies of animals and the bodies of 
plants alike, which exist for the aoul aa their end. End 
used in two senses : the purpose, and the person or 
.^ng which the purpose serves. Soul also means the 8' 
larj source of local movement. This power of local 
vement is not possessed by all living creatures. Trana- 
formation and growth are also due to the soul. For 
sense -perception is supposed to be a kind of trans- 
formation, and nothing is capable of sense -perception 9 
less it has a soul. The case is similar with growth 
id decay. For nothing grows or decays by natural 
processes unless it admit of nutrition, and nothing is 
capable of nutrition unlesa it has a soul. Empedocles 
ascribes downward growth to plants where they are rooted, 
use the earth naturally tends downward, and upward 416. 
iwth, because fire tends in that direction, and in these 
leapeots is not right. For Empedocles does not employ 
the terms up ' and ' down ' correctly. ' Up ' and ' down ' 10 
are not the same for all things nor in all parts of the 
iverse, for roots are to plants what the head is to animals, 
one is to describe oi^ans as identical or different in terms 
their functions. In addition, what principle is it that ti 
lids together these two elements of fire and earth, 
iding, as they do, in opposite directions T For they 
will scatter asunder, if there be no hindering principle. 
And if there is such a principle, it is the soul and the_j 
,£ause of growth and nourishment. Some regard fire as iz 




the real cause of nutriliun and growth. For this seems 
to be the only body or eiemeol that feeds and increases 
itself. One might, therefore, conjecture that this ia the 
element that causes growth and nutrition in animals and 

13 plants. In a certain seuae, it is true, Ere is a co-ordinate 
cause, but not the absolute cause, of growth; this is rather 
the soul. For the growth of fire is indeterminate so long 
as there is material to burn ; on the other hand, in all 
bodies developed in nature there is a limit and signifi- 
cance to size and growth. These attributes ([of limit and 
eiguifieance]) belong to soul, not to fire, to reason rather 
than to matter. 

M- Since the same power of the soul is both nutritive and 
generative, we must first investigate nutrition ; for it is 
by this function of nutrition that the faculty in question 
is distinguished from other faculties. Nutrition is sup- 

ij posed to take place by the law of oppositee, although not 
every opposite is nourished by every otiier, but such 
opposites only aa derive both their origin and their 
growth from each other.' Many things are derived 
from one another, but they are not all quantitative 

iG changes, as e.g. healthy from sickly. Nutrition is not 

' Tbe body in compoBed of bU four elements dud ite aonriahmeat 
mnst inclnde all of tliem. The anim&l wute la BuppUed out of these 
■eTerol elements, which are themaelvea cb»racterized by opposite 
quklitiei, by meana of the action of heat and cold. Blood is the linal 
form into which vital hent cooks the raw food. Arialfltle makaa really 
little aae of the physical explaaatiooa of the Pre-SocraticB, who were 
(atUfied to exptaio all ooBinlcul pbenomena by such opposing foroes in 
nature aa heat aod cold, the moist and dry, the heavy aud light, etc. 
Although Aristotle still makes use of those ideas, in his dynamical 
theory he sees the world full of final causes, while the purely physical 
forues of the Pre-Soaratias are merely tbe instruments employed by soul 
or life. 



1 to these oasea in the same sense, for while water 
ment for fire, fire does not nourish water. The 
■ of food and aourishmeDt appear lo applj par- 

nple bodies. There is, however, a difficulty 17 
S'lHF Qiem are some who maiutain that like is 
Pnourished by like, as like is also increased by like, while 
I others, as we said, affirm the converse of this, viz., that 
I opposites are nourished by opposites, on the ground 
I that like is incapable of being affected by like. Food, 
however, undergoes transformation and is digested, and 
transformatioQ is in every case toward the opposite or iS 
the intermediate. Further, food is aRected by the body 
which assimilates it ; the latter, however, is not affected 
t by the food, juat aa the builder is not aflfected by his 416* 
' material, although the material undergoes change through 
him. The builder merely passes from a state of in- 
activity into one of activity. The question whether 
nourishment is to be understood to apply to the final 19 
[ condition Ib which it ia taken up by the body, or to its 
I original condition, creates a difficnlty. If both are 
meant, only in the one case the food is indigested and 
in the other digested, it would be possible to speak of 
nonrishment conformably to both of the above theories ; 
I for in 80 far aa it is indigested, we should have opposite 
I nourished by opposite; in ao far as it ia digested, we 
should have like nourished by like ; so that in a certain » 
senae, it ia evident they are both right and both wrong. 
Since nothing is nourished which does not share life, the 
object of nutrition would be an animate body as 
animate; so that food is determined by its relation to an 
animate object and is not accidental. There is a 



SI difTerence between the Dourishment and the principle of 
growth ; ia so far as the animate thing is quantitative, 
the notion of growth applies ; in so far as it is a particular 
substance, the notion of nourishment. For food pre- 
serves a being as a substantial thing, and it continues to 
exist so long as it is nourished. Nourishment is pro- 
ductive of generation, not the generation of the nourished 
thing, but of a being similar to it. For the former 

12 exists already as a reality, and nothing generates, but 
merely preserves, itself So then, such a principle of the 
soul as we have described is a power capable of pre- 
serving that in which this principle is found, in so far as 
it is found; nourishment equips it for action. When, 

13 therefore, it ia deprived of nourishment, it can no longer 
exist. Since there are three distinct things here: the 
object nourished, the means of nourishment, and the 
power that causes nutrition, we shall say that it is 
the elemental soul that causes nutrition, the object 
nourished is the body which possesses this soul, and the 
means of nourishment is the food. And since it is fair 
to give everything a name in terms of its end, and since 
here the end of the soul is to generate a creature like to 
itself, the elemental soul might be called generative of 

24 that which is like to itself. The means of nourishment 
is used in two senses, as is also the means of steering a 
ship ; for one may refer to the hand, or to the rudder, 
the one being both actively moving and moved ; the other 
only passively moved. All nutriment must be capable 
of being digested ; heat is the element which accom- 
plishes digestion. Everything animate, therefore, pos- 
sesses heat. We have explained now, in outline, what 


nutriment is. The subject must be more minutely 
treated later on in its proper place.^ 

* SimpliciiiB thinks the referanoe is to De qtMx, ofM/maL and Dt genar, 
el eorr. Sophonias refers to De gener. animoL (724a 14). The reference 
oan hardly be to IlepZ rpo^ as 6arth^lemy-St.-Hilaire (who follows 
Trendelenbnrg) supposes. This latter treatise appears to have origin- 
ated in the Peripatetio School, bat from the fact that it made the 
distinction between veins and arteries it cannot have been Aristotelian, 
and the reference in De aomiL 4566 5 most have been either to a pro- 
jected work or to the early chapters of the Hittor. anim, or to the 
treatises ennmerated by Siroplidos. Of. Zeller^s Ariaiotie^ Eng. tr., 
VoL L p. 98, note. 


Now that we have arrived at the foregoing conclusions, 
let us discuss in general the entire question of ainnr 
gercgg^^ It consists^ bs we have said, in being moved 
and aflTected ;. for it is supposed to be a sort of inte rnal 
^Jbransformation. Some maintain that like is affected bj 
417 a like. In what sense this is possible and in what sense 
impossible, I have explained in a general treatise On 

2 Activity and Passivity} A difficulty is raised by the 
question why it is that perceptions do not arise from the 
senses themselvea^ and why it is that without external 
stimuli they produce no sensation, although fire and 
earth, and the other elements of which we have sense- 
perception, are, either in their essential nature or in their 
attributes, found in the senses. It is, therefore, evident 
that the organ of sense-perception is not a thing in 

3 actuality but only in potentiality. It is consequently 
analogous to the combustible which does not itself 
ignite without something to set it ablaze. Otherwise 
it would have burned itself and had no need of an 

^PhUoponuB thinks the referenoe ia to De gener, tt corr, (cf. 
3236 £). 



Lctive fire. Inasmuch as we say that perceiving is 

ftused in two meauiugs (e.y. we call the capacity to 

liiear and see, hearing and sight, although they may 

I chance to be dormant, and we apply the same terms 

I where the senses are actively exercised), so senae- 

lerception also would be used lii two senses, the one 4 

»tential and the other actual. First of all let us 

l-iinderstand that the terms aSection, motion, and activity, 

I are used in the same meaning. For motion is a sort of 

l.activity, although incomplete, as we have said elsewhere/ 

I'iEverything is affected and set in motion by an active 

■Agent and by something that exists in activity. There- 5 

fore in ooe sense a thing is affected by like, in another 

by unlike, as we have said ; for it is the unlike that is 

aSected, but after being afieeted it is like. 

We must, further, make a distinction touching potenti- 
tality and actuality, for we are now using these terms in 
la general sense. There is a sense in which we speak of 6 
I a thing as knowing, as when we call man knowing, 
le man belongs to. the class of creatures that know 
I and are endowed with knowledge. There is another sense 
I in which we speak of a man as possessing the particular 
I knowledge of grammar. In each of these cases a man r 
possesses knowledge potentially, but not in the same 
sense ; the former is knowing as belonging to a certain 
genus and as having a native endowment; the latter is 
knowing in the sense of being able to exercise his know- 
ledge at will, when nothing external prevents. In a still 
■ different sense there is the man who is actually exercising 
iaJoaowledge, and is in a condition of complete realiza- 
'Phy,. 2016 31, 2676 8. 



tion, having in the strict, sense knowledge of a particnlar 

8 thing, as e.g. A. The tirst two know in a potential sense ; 
the one of them, however, knows when he is transformed 
through a discipline of knowledge, and has passed re- 
peatedly out of an opposite condition; the other knows 

417 # in the sense of possessing arithmetical or grammatical 
science;' and their passing from non-actual to actual 

9 knowledge is different. Again, neither is the term ' pass- 
ivity ' used in an absolute meaning : in one meaning it is 
destruction by an opposite principle; in another meaning, 
it is the preservation of the potentially existent by means 
of the actual and similar, just as potentiality is related to 
actuality. That which possesses potential knowledge, for 
instance, comes to the actual use of it — a transition that 
we must either not call transformation (for the added 
element belongs to its own nature and tends to its own 
^realization), or else we must calll;^ a special kind of 

transformation. It is, therefore, qlfpeSt .to speak of 
thinking as a transformation wlien one -thinks, just as the 
builder is not transformed when he is building a house. 

10 That which conduces to actualization out of a potential 

'These three form* of knowledge itlDHtrftte three Btagei in the 
pMBBge from nndefined potentiaiit; IfiivaiMi) to oompleta and definite 
•atfulibf {Mpytia). From mere ratioDSl potentiality, in which one hu 
DO detiDite latent knowledge, one ptusu into a knowing state by 
repeated application to a given science, and bo from a non-knowing 
condition into a knowing one. On the other hand, if one possenea A 
particular Rcience, ai grunmar, one has definite latent luowledge and 
puses into active knowing, not by acquisition, but by applying what 
one poiMBBes in a dormant or inactive ttate. As a speuifiu potentiality 
I it NpKMtita a higher stage in the progress towards actuEdity, which in 
: cue is the active exercise of specific knowledge. The primary 
potentiality is a person teachable, the second a person tanght, and the 
octoality ia a person actively employing what is taught. 




^■^ T1 
by t 
of ki 

Go !1 




P-e i 

[latter of reasoning and thinking la not fairly 
ig, but must be given another name. Again, 
that which passes out of a potential state by learning or by 
acquiring knowledge at the haods of what actually knows 
id can teach, must either not be said to be affected as 
passive subject, or we must admit two meanings of 
sforroation, the one a change into a ne^tive oondi- 
and the other into a positive condition and the 
ing'a natural state.* 

The first change* in the sentient subject is wrought n 
by the generating parent, but after birth the creature 
comes into the possession of sense-perception as a species 
of knowledge. Active sensation is used in a way similar 
to active thinking. There is, however, this difference, 
that the objects which produce sensation are external, 
the visible and the audible, and similarly other 
ble qualities. The reason for this is that active 12 
Sense-perception refers to particular things, while scientific 
knowledge refers to the universal. These universala, how- 
ever, are, in a certain sense, in the mind itself. There- 
it is in one's power to think when one wills, but to — \, 
;perience sense-perception is not thus in one's power ; / 
sensible object must lirst be present. This also holds' 
of those sciences which deal with sensible realities, 
id for the same reason, viz. because these sensible 

'Aid^toii sigoiSea a tranHiUoDnt ounditioii nnd H" '• pemwuinit, 
tlAtiiral state. The former ii either mere potentiality or an tmperfMt 
■tage in the paau>gB of a thing towards its natural realizatioD. As nich 
it reprMBnts a condition of privation or negatiuo (aTtpTjruij), compaied 
with the positive, completed state .-it which a thing's nature aims. 

t change ' 

a meant the native endowment with the 

68 Aristotle's psychology dbakima 

13 realities belong to the world of particular and external 

To go into the details of these questions would be 
more suitable at another time. For the present so much 
may be r^arded as fixed, viz. that the term * potential ' 
is not used in anj absolute sense, but in one case its 
meaning is similar to our sajing that a boj has in him 
the potentiality of a general, and in another case to our 
saying that a man in his prime has that potentiality — a 
distinction which also applies to the capacity for sense- 

14 perception. Inasmuch as this distinction has no particular 
418 a name in our language, although we have remarked that 

the things are different and how they differ, we must 
simply employ the terms affection and transformation as 
applicable here. That which is capable of sense-per- 
ception is, as we have said, potentially what the sensible 
is actually. It is, therefore, affected at a moment when 
it is unlike, but when it has been affected it becomes like 
and is as its object.^ 

^In other words, sensation represents an 'affection' or impression, 
and is the transformation of a potentially perceiving into an actually 
perceiving subject, in which case the sensible object is also converted 
or assimilated into a knowledge-form. In this sense it is made like 
the perceiving subject. 


In discussing anj form of sense-perception we must 
begin with the sensible object. The 'object of sense' 
is used in three meanings, two of which touch the 
essential nature of sensation and one its accidents. Of 
the two first-named, one applies specially to each par- 
ticular sense, the other is common to them alL By 
* peculiar object of sense ' I mean a sense-quality which 2 
cannot be apprehended by a sense different from that 
to which it belongs, and concerning which that sense 
cannot be deceived, e,g. colour is the peculiar object of 
vision, sound of hearing, flavour of taste. Touch,^ how- 
ever, discriminates several sense-qualitiea The other 
particular senses, on the contrary, (Ustinguish only their 
peculiar objects, and the senses are not deceived in the 
fact that a quality is colour or soimd, although they may 
be deceived as to what or where the coloured or sonorous 
object may be. Such qualities are called the peculiar 3 
objects of particular senses, whereas common objects are 

^ToQoh diBtingaiahes the properties of body m body {De an, 4236 

27), more specificaUy the qualities hard and toft, moist and dry, hot 

and oold, smooth and rough. Moreover, taste is, aooording to Aristotle, 

a kind of haptic fonotion. 


70 Aristotle's psychology dbanim^ 

motion, rest, number, form, magnitude. Properties of 
the latter kind are not the peculiar objects of any sense, 
4 but are common to them all. Motion is apprehended by 
touch and by sight. A thing is an object of sense 
accidentally, e,g, when a white object proves to be the 
son of Diares. The latter is perceived accidentally, for 
the person whom one perceives is an accident of the white 
object Therefore, the sense as such is not affected by 
the sensible object ([as a person]). To the objects of sense, 
strictly regarded, belong such properties as are peculiarly 
and properly sense-qualities, and it is with these that the 
essential nature of each sense is naturally concerned. 


Th2 object of vision is the visible. The visible is colour 
and something whose notion is expressible, but for which 
there is no single definite name.^ What I mean will be 
best explained as we proceed. The visible, then, is colour, 
and this is diffused upon that which is in itself visible,^ 
and by visible 'in itself,' I do not mean notionally 
visible, but something which has in itself the cause of the 
visible. All colour has the power to move the actually ^ig^ 
diaphanous and herein consists its nature. Therefore colour 2 
is not visible without light, but every particular colour is 
seen in the light. For this reason we must first explain 
what light is. Light is something diaphanous. By dia- 
phanous I mean that which is visible, though not in itself and 
absolutely, but only by means of an agent, namely colour. 
Of such nature is air and water and many other bodies. 3 
Water and air are not diaphanous as water and air, but 
because there is in both these elements the same property 
that is found in the eternal empyrean. The activity of 

^Snch phosphorescent and scintUlating subetances as mashrooma, 
horn, fish-heads, etc. Vid. De an. 419a 5. 

' Colour is not a substance but a property, a property diffused on the 
surface of a body and has the power to move a diaphanous medium. It 
is the coloured thing which is the substance or the per ae visible. 


72 Aristotle's psychology dbakima 

4 this diaphanous, as such, is light But where the 
diaphanous exists only potentially, there is darkness, 
light is the colour, as it were, of the diaphanous, when 
the diaphanous is made really so by fire or by some such 
agent as the supernal body, for in the supernal body 

5 there is something which is identical with fire. The 
nature of the diaphanous, therefore, and of light has been 
explained. Light is, namely, neither fire nor in a word 
any body nor the efflux of any body^ (for this would then 
also be a body), but it is the presence of fire or some 
such agent in a diaphanous medium. For two bodies can- 
not occupy the same place at the same tima Light appears 
to be the opposite of darkness. Darkness is the privation 
of a condition of the diaphanous, the presence of which 

6 condition is light. Empedocles^ is wrong, as is every one 
else who has held a like theory, in thinking that light 
moves itself and at some time or other projected itself 
into the interval between the earth and the surrounding 
space, without our being conscious of it. For this is 
contrary to plain reason and to observed facts. In 
a small space, the fact might escape us, but in an 
interval that extends from east to west, to claim that the 

7 fact escapes our notice is asking too much. It is the 
colourless that is receptive of colour, and the non- 
sonorous that is capable of sound. Colourless are the 

' diaphanous and the invisible, or that which is scarcely 
visible, as for example, the dark. Of such nature is the 
diaphanous, but only when it is so potentially and not 

^ Plato, TimaeusdlC, 

'Burnet thinks that Empedocles was led to sappose that light takes 
some time to travel, although its speed is so great as to be imperceptible, 
by this theory of ''efQuenoes." Burnet, Ecurly Oreek PhiloB. p. 266. 


Actuallj. For the same medium is sometimes dark and 
sometimes light Not all objects are visible in the light, 8 
but only the peculiar colour of each object. For certain 4x9 « 
objects are not visible in the light, but stimulate sensa- 
tion in the dark/ as t,g, those fiery, shining phenomena 
that have no class-designation such as mushrooms, horn, 
and the heads, scales, and eyes of fish, while the peculiar 
colour of none of these objects is seen. The explanation 9 
of their visibility is subject for a different treatise than 
the present So much is now clear : it is colour that is 
visible in light Therefore without light colour is not^ 
visible. For it is the essence of colour to set the 
actually diaphanous in motion, and the diaphanous in 
actuality is light Clear evidence of this is the fact that 10 
if one places a coloured object on the eye, it is not seen. 
On the contrary, it is the diaphanous, as t,g. the air, 
which is stimulated by colour, and the sense oigan is 
stimulated by this contiguous medium. Democritus is 
wrong, then, in supposing that if the medium were a 
vacuum our vision would be accurate, even to the seeing 
of an ant in the sky. This is impossible, for vision takes 
place firom the fieu^t that the percipient organ imdergoes u 
an effect, and this effect cannot be produced directly by 
the visible colour. So that there remains only the 
supposition that it is produced by a medium, and conse- 
quently there must be a medium. And were a vacuum 
produced, there would not only be no accurate vision, but 
no vision at all.^ 

^ Phosphorescent rabstancee. 

' Aristotle says there are three things to be taken into aoooont in sense- 
perception — the organ, the object, and the medinm, all of which are 
€(mdicMmu atne qwlbw fum. The medium of virion is the diaphanous or 

74 Aristotle's psychology deahma 

12 The reason why colour is visible only in the light has 
been explained. Fire, however, is visible in both light 
and darkness, and necessarily so, for it is by the agency 
of fire that the diaphanous becomes diaphanous. The 

13 same statement applies also to sound and smell. For 
nothing when placed in actual contact with the sense- 
organ produces the sensation of sound or smell, but by 
means of odour and sound a medium is set in motion and 
through this the sense organ in each case is affected* 
But if one should place a sonorous or odorous object on 
the sense organ itself, no sensation would be produced. 
In the case of touch and taste, similar conditions hold 
good, although not apparently. The reason for this 

M will be evident later. The medium for sound is the 
atmosphere ; the medium for smell has no nama It is 
an element that is common to air and water, and aa 
the diaphanous is related to colour, so there is a some- 
thing in water and air similarly related to an odorous 
body. For aquatic animals appear to be capable of the 
^ig ^ sensation of smell. But man and the respiring land- 
animals smell only in so far as they employ inspiration. 
The cause of these phenomena will be explained later on. 

property of translacence found in air and water, a quality analogous to 
that found in the aether of the empyrean and in fire. The media of 
hearing (4196 18, 420a 11) and smell are air and water, and the medium 
of touch (and taste) is the flesh. Li this connection it is to be noted 
that, while both air and water serve as media for smeU, only air is a^ 
medium for man, and only water a medium for the aquatic animals. 
Man cannot smell in water. Cf. De an, 4216 8, 15, 19; 422a 4; 
Hist, anim, 534a 11. 


Let us now first of all discuss the subject of sound and 
hearing. Sound is twofold. It is one thing in actuality, 
and another in potentiality. Some things, we say, are 
incapable of sound, such as a sponge or wool, others are 
resonant, such as bronze and bodies that are hard and 
smooth, because they can emit sound ; that is, they have 
the power to create an actual sound through mediation 2 
between the resonant object and the hearing. The actual 
sound is always produced by something in reference to 
something and in a medium.^ A blow is the producing 
cause. It is, therefore, impossible for an object, taken 
alone, to produce a sound, for the striking agent and the 
struck object are dififerent. Thus the sonorous body pro- 
duces sound by its relation to another body. A blow is 3. 
impossible without movement, and, as we have said, sound 
does not result from a blow upon any haphazard object. 
Wool, e.g. when struck produces no sound, but bronze 

^ TheophrMtoB and the peripatetic commentaton introduced the 

term Siirx^ to describe the medinm of sound and ^Loaiun^ to describe the 

mediam of smeU. Cf. Themistius, ed. Spengel, p. 116. Simplicias 

QommaU in lib. De cm,, 419a 32. Philoponus Comment in lib. De an. 

(Ed. Acad. Reg. Bor.), 355. U. 




and whatever is hard and smooth do. Bronze is resoaant 
because it ia smoolh. Hollow bodies, by reverberation, 
produce many reports after the first one, because the air. 
when it is once set in motion, can find no egress, 

4 Furthermore, audition takes place in air and water, but 
to a less degree in the latter. But neither air nor water 
ia the main thing in the case of sound. The percussion 
of solid bodies against each other and against the air 
must take place, and this takes place when the smitten 

j air resists and is not dissipated. Therefore if it is stnick 

< quickly and violently it produces sound, for the motion of 
the striking agent must anticipate the dispersion of the 
air, as if one were to strike a pile or rapidly shifting 
chain of sand. An echo is produced when from the air 
which is made unitary bj means of the vessel that confines 
it and keeps it from dispersion, an oncoming mass of air 
is driven back again, like a rebounding ball.* An echo is 

6 apparently produced constantly, only it is not audible, 

''SoQDil, according to this explanatioit, U produced by amootb, 
resiating bwliea. The production of sound depends on the following 
conditions ; (1) an object to be atruck, (2) a strilcing agent, (3) a com- 
municating medium, (4) > hearing organ, (6) the debvery of the blow 
in such way tbat the diffluent air (medium) may not be dissipated and 
■o conduct DO sound. When the air ia eniitten quickly and vigorously, 
it ia oompresacd before it can yield, and so emits a report, as tlie com- 
pcened air in a bladder makes a report on bursting (an illuBtmtioD 
cited by Wallace from PaeiiiB), An ei;lio ia the ropeteuasion of air 
from the resisting aide of a vessel or place that obstruots tbe dissipation 
o( air, whereby instead of becoming soundJcss it ia thrown back, like a 
ball, and made to sound again. The disturbed air communioates with 
the air in tbc ear, which being immared cannot be diaaipated, 
but interprets without variation the reporta bronght to it by the move- 
ments of the external air. Diaturbanoes in tbe condition of tbe internal 
ftir, e.;;. through yawning, modify the accuracy of hearing. We, 
also, for the same reason hear better when iobaling than when exhaling 
{Deotner. anim. ^S\a Si}. 



for the same conditions hold good of both sound and 
light light is constantly reflected (otherwise light 
would not be found everywhere, but there would be 
darkness outside the r^on illuminated by the sun), but 
the reflection is not similar to that which is caused by 
water or bronze or any other polished solid, where a 
shadow is cast whereby the light-area is delimited. A 7 
void is correctly regarded as a chief factor in hearing. 
Now, the air appears to be a void, and this, when it 
is moved as a single and continuous element, is what 
produces hearing. But, because of the swift dissipation 
of the air, no sound arises unless the object struck be 
smooth. In this case, however, the air by reason of 4200^ 
the even surface, is made one throughout, for the surface 
of a smooth body is one throughout 

A body is sonorous when it is capable of setting in \ 
motion up to the organ of hearing the single and con- 
tinuous air. Hearing is naturally related to the air, and\. 
owing to the fact that sound is in the air, the inner air S 
is set in motion by the moving outside air. Therefore, 
an animal does not hear in all parts of its body, neithec^ 
does the air penetrate everywhere. And the psychical 
organ that is to be stimulated does not contain air in all" '^ 
its parts. The air in and for itself is, by reason of its 
facile dispersion, non-sonorous. But when it is restrained 
from dispersion, its motion produces sound. The air ^ 
within the ears is so deeply immured as to be in itself 
immovable, in order that it may detect all distinctions in 
communicated motions. For these reasons we hear in 
water, because the water has no access to the congenital 
air, nor does it penetrate even into the ear because of the 



letter's convolutions. When, however, this does happen, 
hearing ceases. Neither do we hear when the membrane 

10 is diseased, just as the eye has no vision when its cornea 
is diseased. A test as to whether hearing is intact or not 
is found in the ears' continually resounding like a horn. 
The air in the ear has its own peculiar motion, although 
sound is foreign to this internal air and is not one of its 
properties. It is for this reason that we speak of hearing 
by means of a void and resonant organ, because we hear 
by means of something which contains confined air. The 

M question arises whether it is the striking agent or the 
object struck that produces sound. Or is it both of 
these, but each in a different sense ? Sound is a sort of 
motion of an object which is capable of being moved in 
the same way as the particles that rebound from smooth 
surfaces when one strikes them. Not every object, as 
has been said, produces sound when atnick or when 
striking another object, as e.g. in the case of one sharp 
point striking another. On the contrary, the object that 
is struck must be smooth, so that the air may be thrown 

12 off and agitated in a mass. Distinctions in resonant 
bodies are discernible in the actual sound they pro- 
duce. As without light no colours are visible, so without 
sound the acute and grave are not discernible. These 
terms are employed metaphorically and are drawn from 

13 the tactual sense. The acute stimulates sensation quickly 
and strongly, and the grave slowly and in a small degree. 
It is not the acute,* however, that is quick nor the grave 
that is slow, but merely the motion of the one is called 

I Trendalenboi^ DEFINITION OP VOICE 79 

quick by reason of its S¥dft action on the sense, and the 
other is called slow by reason of its tardy action. The 
analogy appears to apply to acute and dull in the sense 
of touch. The acute t,g. pricks and the blunt pushes, 420^ 
as it were, because the motion of the one is quick and of 
the other slow, so that the efifect of the one takes place 
swiftly and of the other tardily. Let so much sufBce for 14 
the discussion of sound. 

Voice is the sound produced by a living being. NoN 
inanimate thing has voice, unless one speaks metaphori- 
cally, as e.g. the flute, lyre, and other inanimate 
instruments are said to have a certain range, melody, and 
expression, properties which are possessed also by the 
voice. Many animals are without voice, as the 
bloodless animals, and, amongst the sanguineous, fishes. 
This has its good reason, seeing that sound is a move- 15 
ment of the air. Fishes that are said to have voice, 
such as those in the Achelous,^ produce a sound by 
means of their gills or some such organ. Voice is the • 
sound made by a living creature, and made not by any • 
accidental organ. But since nothing emits sound unless 
there is a striking agent, a thing struck, and a medium, 
viz. air, it would be reasonable to suppose that only 
those animals that breathe air possess voice. Now 
nature employs respiration for two purposes, just as she 16 
employs the tongue both for the function of taste and of 
speech, of which functions taste is necessary (and therefore 

^Referred to in Hist, amm, (Bk. IV. Ch. 9, 5356 18) as <rdrpof, nid 
to make a gmnting noise, which probably saggested the name {Kdwpot 
meaning primarily a wUd boar). It is not known to what fish this 
refers, although it has been thooght to be the ettproa aper of the Aegean 
Archipelaga Cf . Anbert and Wimmer's AruMda^ ThUrhwnde^ p. ISO. 

80 Aristotle's psychology deakima 

is found in all animalfi generally), whereas the communi- 
cation of thought is given for the ends of higher living. 
So it is with respiration, which performs a function in 
reference to the internal warmth, and as such is neces- 
sary for living (the reason will be explained elsewhere),, 
and another function in reference to speech, where it 
subserves the ends of higher living. The windpipe is the 

'7 organ of respiration, and this organ in turn subserves 
another, the lungs, and it is in virtue of the latter that 
land animals have more heat than others. The pericardiac 
region first of all needs respiration,^ and, therefore, it 
is essential that the air be inspired inwards. And 
so it is the percussion of the inspired air, directed by 
the soul in those inward parts, against the windpipe, 

iS as it is called, that constitutes voice. Not every sound 
of an animal is voice, as we have said (for it is possible to 
make noises with the tongue or such as people make in 
coughing), but the impact of the air must be animate 
and combined with some idea in order to be called voice. 
For voice is significant sound and not merely the sound 
of respired air, as is the case in coughing. On the 
contrary, the animal by means of this respired air pro- 
421 a duces-ftn impact of the air already in the windpipe against 

^The organs through which cooling is efifected are the brain and 
langs, and in the case of fishes the gills. The need of cooling is 
f onnd in different degrees in different animals. Bloodless animals need 
it least. Insects do not inhale, but they are provided with a substitute 
for inspiration in a supply of congenital air. (Z>e respirat, Ch. 9, 4746 
26 ff ) The lungs of mammals contain most blood, while the lungs of 
birds and amphibious creatures are more spongy and contain most air, 
and the latter can consequently live longer without inspiring air. 
The air is carried through veins that lead from the lungs to the heart. 
Hist. aninuU. Bk. I. Ch. 17, 496a 27 ff. 


the trachea itself. This is proven by the impossibility 19 
of vocal utterance when we neither inhale nor exhale but 
simply hold our breath, because in holding the breath we 
thereby disturb this vocal process. Also, we see from 
this why it is that the fishes have no voice, being, as 
they are, without a windpipe. They lack this organ, 
because they are incapable of inhaling or exhaling air. 
The explanation of this is matter for a dififerent treatise. 


Smell and its object are less easy to define than the 
foregoing senses, for the nature of smell is not so clear 
to us as is that of sound and colour. The reason for this 
is the fact that this sense with us is inaccurate and less 
perfect than in many animals. Man has a poor sense of 
smell, and smells no odorous object without painful or 
pleasant association, because the sense-organ does not 

2 sharply discriminate qualities. It is probable that the 
hard-eyed^ animals discriminate colours in the same 
way, and that distinctions in colour are not clear to them 

3 except as they have the feeling of fear or not. So it is 
with smell in the human race. Smell has apparently 
some analogy to taste, and the species of flayours corre- 
spond to those of odours; but our sense of taste is more 
accurate because it is a sort of touch, and the sense of 
touch is the most accurately developed of all the senses 
in man. In the case of the other senses, man is inferior 
to many animals, but in discriminations of touch he is 

4 far superior to the others. For this reason man is the 
most intelligent animal. A proof of this is the fact that 
within the human race the good or bad native endow- 

1 HUt. anim. ii. 13, 606a 36 ; iv. 10, 6376 12 ; De parL anim, 
ii. 13, 6676 34. Such animala have no eyelids, as e,g, crabs. 



ment of individuals depends upon this sense organ, and 
no other. Men who have hard flesh are poorly endowea\ 
intellectually, men who have soft flesh are gifted.^ 

As one flavour is sweet, another bitter, so it is with 5^ 
smeUs. Although in some cases smell and flavour 
correspond to each other, — I mean, for example, where 
we have a sweet smell and a sweet flavour, — ^in other 
cases they are contraries. In like manner we refer the 
qualities of pungent, harsh, piquant, and oily to smells as 6 
well as to flavours, but, as we have said, owing to the 
fact that smells are not so clearly discriminated as 
flavours, these terms are borrowed from taste on account 
of similarity in the sense objects. For the smell of 421 ^ 
safifron and honey is sweet, and the smell of thyme and 
similar herbs is pungent. The same holds good of other 7 
qualities. Further, just as hearing and each particular 
sense distinguishes its own object, in the one case the 
audible and inaudible, in another case the visible and 
invisible, so also smell distinguishes the odorous and 
inodorous. And the inodorous is so called, in one case, 
from the fact that it is totally incapable of yielding 
smell; in another case because the smell is faint or 
indefinite. Similarly one employs the term insipid. v^,^ 

Smell is transmitted through a medium, such as air otA 
water. For aquatic animals appear to smell; so, too, 
sanguineous and bloodless animals, and the birds of 
the air, have this sense. Some of the latter are ^dowed 
with the power of scent and mark their prey from afar. 
It seems doubtful, therefore, whether the process of smell 9 
in all these animals is alike. Man smells while inhaling, 

^ Compftre our ezprenions ' thiok-akmned,' ' hide-bomid,' etc 



but without inhaling and while exhaling or holding his 
breath, he does not smell, whether the object be remote 

lo or near, not even if it be placed in the nose iteelf. That 
an object when placed upon the sense-organ itself is not 
perceived, is a fact common to all the animals. But not 
to perceive odours without inhaling is peculiar to man, as 
may ' be proven by experiment. Were it not so, the 
bloodless animals, inasmuch as they have no respira- 
tion, would have to possess a sense beyond those already 

■I named. But this is impossible, if it is true that they 
perceive smells, for the perception of the odorous, whether 
pleasant or unpleasant, is the sense of smell. Further- 
more, as these animals appear to be destroyed by strong 
fumes, just as man e.g. is destroyed by pitch, sulphur, 
and similar fumes, they must have the sense of smell, 

12 although they do not respire. The oi^n of smell in 
man appears to difier from that in the other animals, just 
as bis eyes difter from those of the haid-eyed animals. 
For the eyes in man have a protection and, as it were, a 
sheath in the eyelids, and without moving or opening 
these he does not see. Whereas the hard-eyed animals 
have no such protection, but see at once whatever comes 

13 into the field of vision. So also the organ of smell in 
Vi" some animals is uncovered, as the eye is; while in others 

that respire, it has a covering, which opens in inspiration 

14 and by the dilation of veins and pores. For this reason 
the animals that breathe do not smell in water. For in 
order to smell they must inhale, and in water this is 
impossible. Smell is a property of the dry, as flavour is 
of the moist, and the organ of smell is potentially 
analogous to its object. 


The sapid is a tactual property, and this explains the 
fact that it is not perceived through the medium of any 
foreign bodj.^ For neither is the tactual so perceived. 
The body in which flavour, i,e. the gustable, is found 
consists in something moist as its matter, and this moist 
element is something tangibla Consequently, if we were 
in the water and something sweet were thrown into it, 
we should perceive it The sensation, however, would 
not have been produced in us through a medium, but by 
tile mingling of the sweet with the moist, as is the case a 
with a beverage. Colour, on the other hand, is not per- 
ceived by means of its being mingled with anything, nor 
by means of emanations. There is in the case of taste 
no medium; in other respects, however, as colour is to 
the visible, so is taste to the sapid. Nothing can stimu- 
late the sensation of flavour apart from the moist, but an 

^ The mediam of toaoh is the fleeh. The mediam of taste is also the 

flesh, more particularly the tongae and throat (if Aristotle oonoors in 

the popular opinion represented by Philozenns, cf. Eth, nicom. iiL 10. 

IOl 1118a 33). These two senses, consequently, apprehend qualities 

only through immediate contact, while sight, hearing, and smeU operate 

at a distance through the media of air and water. 


86 Aristotle's psychology okakima 

object must possess moisture either actually or potentially, 
3 as does salt. For salt is easily soluble, and melts on the 

As sight is discriminatiye of the visible and invisible 
Xfor darkness is the invisible, and on this, too, sight 
exercises judgment), further of the extremely dazzling 
(for this is also invisible, but in a different sense from 
darkness), so, too, hearing is discriminative of sound and 
silence, of which the one is audible and the other 
inaudible, and of the crashing sound, as sight is dis- 
criminative of dazzling brightness (for as a tiny sound is 
inaudible, in a certain sense a great and crashing sound 
is also inaudible). The term invisible is used, on the 
one hand, in an absolute sense, and means the same as 
the term impossible does in other cases; on the other 
hand, it is used in the sense of what is naturally meant 
to be seen, but is not seen, or only imperfectly seen, 
just as one applies the terms footless and seedless to 
animals and fruits that are imperfect. So also is taste 
4-iiiscriminative of the gustable and non-gustable ; the 
latter is that which has an insignificant or indistinct 
flavour, or a flavour that is subversive of taste. The 
potable and non-potable seem to be the final principles 
of taste ; taste implies both of them. The one is, how- 
ever, indistinct or destructive of taste, while the other is 
natural to the sense. The potable is common to the 
422 b senses of touch and taste. Since the sapid is moist, it is 
necessary that the sense-organ be neither actually moist 
nor incapable of becoming moist. For taste is affected 
5 by the sapid object as sapid. Consequently it is 
necessary for the organ of taste to be capable of becoming 


loist, without injury and without becoming intrinsically 

moist.^ A proof is the fact that the tongue, when it is 

I yery moiat or very dry, is incapable of perceiving the sapid. 

I For in this case there arises merely a tactual impression 

" of the simple liquid, just as when ons first tastes a strong 

flavour and then essays another, or as everything seems 

bitter to an invalid because his tongue is full of this 6 

bitter moisture. The varieties of flavours, as in the case 

of colours, are partly simple opposites such as sweet and 

bitter, partly the affiliated qualities oily and salty, and 

the intermediate qualities of pungent, harsh, astringent, 

and acid. For these aeem to include approximately all 

, the distinctions in ttavours." So then the sapid sense is 

I potentially of the same character as the sapid object 

' which actually produces the sensation of taste. 

' Aristotle ftpplies here to tute the metaphysical doctriiie of poteo- 
tiAlity and aotnality wbich he employi everywhere in the explanitiou 
<rf organic life. All change U a. trBuaitWD £rom a potential state into a 
Q which a thing; Bods its end realLxed or in prooeu of realiution. 
f So the tente of tMte is only potentially tjute anlil it is atimalated. In 
NiaBa of actnalization or realization the organ assimilates an 
objeotive qnality and caoverts it iato a sabjeotive one, to use modern 
terminology, and thii procesa Aristotle describes as the "sense becom- 
ing like the thing," or, specifically, the "capacity of the organ of taste 
to become moist, without being converted into moisture, or becoming 
intrinsically moist." The poteottality of the organ refers only to the 
ksmmilation of a property or sense- qnatity. 

'Aristotle diatinguiahea two fundamental colours, black and white 
[which on surfaces correspond to darkness and light), and two funda. 
mental t«st«i bitter and sweet. Including block and white, there are 
•even primary colonrs, all of whose elements, however, are found in 
black and white, and they are produced from these two by prooeasaa of 
mixture. Theae colours are white, blaok (including grey, De ecTuu, 
442lt 22), yellow, red, violet, green, and bine. Analogously the seven 
primary tastes are bused on bitter and aweet. The Qavours Ike : sweet 
(including the fat or oily), bitter, salt, faarsh, pungent, MtriDgent, aoid 


The same kind of reasoning applies to the tangible and 

^ the sense of touch. If touch is not a single sense but 
several, then tangible objects must also be manifold. 
There is some doubt whether touch is manifold or 
unitary, and it is uncertain what the sense-organ is 
which apprehends the tangible. Is it the flesh in 
man, and in other animals something analogous to flesh, 
or is the flesh only the medium, while the primary 

2 organ is something diflferent and internal? Every 
sense appears to apprehend only one contrary, e.g, sight 
senses black and white ; hearing, acute and grave ; taste, 
bitter and sweet. In touch, however, are found many 
opposites: hot and cold, moist and dry, hard and soft, 
and other similar opposites. There appears, however, to 

3 be a solution for this difiiculty in the fact that several 
opposites apply to the other senses also, as e.g. in sound 
there are not only the properties acute and grave, but 
also large and small, and smooth and hard, and similar 
qualities are applied to the voice. Similarly, different dis- 

4 tinctions are applied to colour. But what forms the single 
substrate for touch, as sound does for hearing, is not clear. 




Anotber question is whether the sense-organ is iuteraal ' 
lor not, or whether the fleeh immediately senaeB touch- 
r qualities. The fact that seneation is simultaneous with 4230 
I contact is no proof here. For as a matter of fact, If one 5 
should prepare a membrane, as it were, and draw it over 
the flesh, one would still have the sensation of touch at 
the moment of contact, and yet it is plain that the sense- 
organ is not in the membrane. Even were it grown 
[ blether with the flesh, the sensation would only the 
I more quickly penetrate it. ConBequently this part of the 6 
I body seems to be related to us as the air would be, were 
it grown to us round about. Tor we should then have 
I to perceive sound, colour, and smell in each instance 
I by means of a single sense-organ, and sight, hearing, 
■ and smelling would in that case have become a single 

However, as a matter of fact, since the media through 

which sense-movements are transmitted are ditferent, the 

sense-organs themselves are different. In the case of 7 

touch this is not clear ; for it is not possible that a living 

body should consist of air or water ; it must be a solid 

[ body. It remains that it is a body composed of earth 

\ and those two former elements, air and water, in such way 

it is intended flesh and what is analogous thereto 

llBhould be. Consequently, the body ([i.e. the tieshj) must 

be the natural medium for the sense of touch, by which the 

several sensations are mediated. That they are several 8 

is evident from the character of touch on the surface of 

. the tongue. For the tongue, as a single organ, dis- 

l cerns all tactual and sapid qualities. Further, if the 

; of our Besh were to discern sapid qualities, touch 

90 Aristotle's psychology dxanima 

and taste would be regarded as one and the same sense. 
But as a matter of fact they are regarded as two, because 
they are not convertible. 
9 Since body has depth, i.e. the third dimension, wherever 
there is an intermediate body between two other bodies 
the question might be raised whether it is possible for 
these two bodies to be in contact with each other. Now, 
neither the moist nor the fluid is incorporeal, but each 
must necessarily be water or contain water. But objects 
which are in contact with each other in the water, inas- 
much as their extremities are not dry, must have water 
between them, in which their outer circumferences are 

10 submerged. Now, if this is true, it is impossible for two 
objects in water to be in contact with each other. The 
same holds good of the air (for air is conditioned in the 
same way towards the objects in it as water is towards 
objects in water, only in the former case the conditions are 
more elusive for us ([who live in an atmospheric medium]), 

11 just as aquatic animals fail to observe that the fluid is in 
423 6 immediate contact with the fluid. A further question then 

arises, whether the same process of sensation applies to all 
senses alike, or whether in different senses the process is 
different, just as touch or taste was seen to function by 
means of immediate contact, while the other senses function 
from a distance. This last distinction is not real, but 
both the hard and soft we perceive through media, as we 
do also the sonorous, the visible, and the odorous; in the 
one case we have objects at a distance, in the other, close 

12 at hand. This is the reason why the medium eludes our 
observation. For we do sense everything through a 
medium, but in the case of things close at hand, the 


existence of the medium escapes us. And yet, as we 
said above, weie we to perceive all tangible qualities 
through the medium of a membrane without knowing that 
a medium intervened, we should then be in the same 
condition as we now are in the media of air and water. 
For we appear now to be in contact with things them- 
selves, and not to apprehend them through a medium. 13 
The tangible, however, differs from the visible and audible 
in that we perceive the latter by the medium producing 
a certain effect on us, while qualities of touch we do not 
perceive by means of the medium but simultaneously 
with it, as a man who is struck through his shield. For 
the struck shield does not strike him, but rather shield 
and man are simultaneously struck. In a word, flesh 14 
and the tongue seem to be related to the sense-organ as 
air and water are severally related to sight, hearing, and 
smelL For were the sense-organ itself brought into con- 
tact with the object, sensation would not result either in 
the one case or the other, just as little as vision would 
result were one to lay a white object on the surface of the 
eye. By which it is evident that the organ of touch 15 
must be internal,^ for in this way it would be parallel 
with the other senses. When objects are placed upon 
the sense-organ, sensation does not result ; on the other 
hand, when placed upon the flesh, sensation does result. 
Flesh must, therefore, be merely the medium of touch. 

The distinctions of body as body are tactual. By dis- 16 
tinctions I mean such as characterize the elements — viz. 
warm and cold, dry and moist, concerning which we have 

' The organ of taste and touch is the heart ; the media, as already 
explained, are the tongue and flesh. 

92 Aristotle's psychology dbahima 

spoken in an earlier treatise On Oie dements} The sense- 
organ which perceives these distinctions is touch, and the 
part in which the sense of touch, as we call it, is primarily 
found is potentially what tangible objects are actually. 
17 For sensation means being affected in a certain way; so 

424 a that whatever makes another thing to be in reality like 
itself does so by virtue of that thing's having this nature 
in potentiality. Therefore we do not perceive hot and 
cold, hard and soft, in objects that have these qualities in 
like degree as ourselves, but we perceive the excesses, as 
if sense were a sort of mean between opposed sensible 
objects. And hence it discriminates sensible objects. 

^ • 18 The mean is capable of judgment, for it becomes in refer- 
' ence to each of the extremes another extreme. And as 
that which is to perceive white or black must not itself 
be actually white or black, but both of these potentially 
(and the same holds good of other instances), so also in 
the case of touch, it must not be either hot or cold in 
itself. Furthermore, as sight was said to discriminate in 
19 a sense both the visible and invisible, and the other 
senses in like manner their opposites, so also touch 
discriminates the tangible and intangibla And by 
intangible I mean those things where tactual discrimina- 
tions are quite indistinct, as e,g. in the case of air, and 
those excesses of touch that are destructive of the sense. 
Each of the senses has now been treated in outline. 

^ Dt gen, et corr. 3296 18-3906 9. On the lost treatise -rtpi moix^iw 
see Heitz, Die Verhrenen SchrifUn d, Aristoteles, p. 76. 


In reference to sensation in general we most understand \ 
that a sense is capable of receiving into itself sensible / 
forms without their matter, just as wax receives 
into itself the mark of a ring without its iron or 
gold; — it receives into itself a gold or bronze im- 
pression, but not as gold or bronze. In like manner 
also sense is impressed by every object that possesses 
colour or flavour or sound, not in so far as each of 
these objects bears a given name, but in so far as it has 
such and such a quality and expresses an idea. The 
organ of sense is fundamentally that in which th 
power of being impressed exists. It has therefore an 
identity with the object that makes the impression, but 
in its mode of expression it is different. Otherwise that 
which perceives would be a sort of magnitude ; whereas 
the mode of expression of the perceptive faculty and of 
sensation is not magnitude, but only a certain relation 
and potentiality of magnitude. From this it is clear 
why excesses in sensible objects destroy the sense-organs. 3 
For if the stimulus be stronger than the organ, then the 
relation between them is destroyed, just as harmony and 
tone are destroyed when the strings are struck too 



9i Aristotle's psychology dianima 

^^ violently. Why is it, then, that plants have no sensation, 
having as they do a certain psychical endowment, and 
being afiTected by tangible qualities, for they experience 

4H^ e.g. cold and heat? The reason is that they have no 
mean in their nature, nor such a principle as is capable of 
receiving into itself the forms of sensible objects ; on the 

5 contrary they are affected materially. One might raise 
the question whether a thing which cannot smell can be 
affected by odour, or that which cannot see can be 
affected by colour, and so on. Supposing that the object 

6 of smell is odour, odour produces the sensation of smell, 
if it produces anything at all ; so that nothing which is 
incapable of smelling can be affected by odour. The 
same reasoning applies to the other senses. Neither can 
sentient beings be affected further than they are in each 
case sentient This is also evident from the following : 

^ neither light nor darkness, sound nor smell, acts upon 
bodies, but the media in which these qualities exist 
may act upon bodies, e.g, it is the air which is 
combined with thunder that rives the tree. Tangible 
>^ualities, however, and flavours operate directly. If 
this were not so, how could inanimate bodies be 
affected and changed ? Do the other qualities then 
act directly also? Or is it rather true that not every 
body is capable of being affected by smell and sound, and 
those which are so affected are indefinite and unstable, as 
e.g. the air ? For air emits odour as if it were affected by 
something. What is smelling, then, beyond this being 
affected by something? Smelling surely means also 
perceiving, whereas the air by being affected is only made 
the ready object of perception. 

V - 

' /• 



That there is no additional sense beyond the five we 
have enumerated (I mean sight, hearing, smell, taste, and 
touch), one may believe from the following considerations. 
Granted that we really have perception of everything for 2 
which touch is the appropriate sense (for all the qualities 
of the tangible as such are apprehended by touch), it is 
necessary that if any sensation is lacking, some oigan 
must also be lacking in us. Whatever we perceive by 
contact is perceived by the sense of touch, with which we 
are endowed. On the other hand, whatever we perceive 
through media and not by direct contact, is perceived by 
simple elements, such as air and water. The conditions 
here are such that if several sensible objects which differ 3 
from each other generically are perceived by a single 
medium, then anyone who has a sense-oigan analogous 
to this medium must be capable of perceiving these 
several sense-objects. For example, if the sense-organ 
is composed of air and the air is the medium of both 
sound and colour, the organ would perceive both these 
sense-qualities. If, on the other hand, several elements 
are mediators of the same sense-qualities, as eg. colour is 425 a 




mediated both by air and water (for both are diaphanous), 
then the organ which contains one of these elements 
alone will perceive that which is mediated by both of 

4 them. The senae-organa are composed esclusively of these 
two simple elements, air and water (for the pupil of the 
eye is composed of water, the hearing of air, smell of 
one or the other of these). Fire, however, belongs to no 
oi^an or it is common to them all (for nothing is sentient 
without heat). Earth belongs either to no organ or it is 
chiefly and in a special manner combined with touch. 
Nothing would remain, therefore, excepting air and water, 

5 to constitute a sense-oi^an. Some animals have, in 
actual fact, these organs as described. Animals which are 
perfect and not defective have all these senses. For 
even the mole, as one may observe, has eyes underneath 
its skin. Consequently, unless there are bodies other 
than those known to ua. or qualities other than those 
which belong to earthly bodies, we may conclude there 
is no sense lacking in us.^ 

6 Neither is it possible that there should be any peculiar 
organ for the perception of common properties such as 
we perceive accidentally * by means of the individual 

'The argument here, that there can be no sensea beyond the five 
enntuerftted, is hopeleasly obaonre. The statement of the nrgnmeDt 
ii probably fragmentary. Burtbi^lemy-St-Hiiaire {Traiti de CAiiit, p. 
2M, Dote] wrongly reatatea the ■rgomeat, in hia attempt to put an 
intelligible mesuiDg into it, and ZeUer'B rehabilitation of it (Eng. tr. vol. 
I. p. 62) IB not less obscure than the puBage itself. The argument 
apparently aimed to show that we are equipped with aenac-orgons to 
cognine the qaalitiea of all known bodies, and. oa nature does oot iin- 
neceasarity duplicate these organs, they moat be complete. 

'Omit Di^, which Biehl has incorporated into his text from Toratrik'a 
donjeoture, agoioat the better reading of ull the uss. The emendation 
antirely destroys the aenae ot the paaaage, it being the reiterated 


senses, e,g, common properties like motion, rest, form, 
magnitude, number, unity. For all these properties 
we perceive by means of motion, e,g, magnitude is per- ^ 
ceived by motion. So also is form, for form is a sort of 
magnitude, and rest we perceive from the absence of 7 
motion. We perceive numbers by the negation of con- 
tinuity and by the special senses, for each sensation is 
experienced as a unit. So, then, it is clearly impossible 
that any particular sense should apply to these common 
properties, such as motion. For this would be like one 
now perceiving the sweet by means of sight. This is s 
because we happen to have senses for both qualities ([{.e. 
for the sweet and for colour]), whereby when the given 
qualities coincide in one object, we recognize the object 
as sweet.^ Otherwise we do not perceive the sweet, 
excepting in the sense of accident, as e,g, when we 
recognize the son of Cleon not because he is Cleon's son, 
but because he is a fair object, which for the son of 
Cleon is an accident. 

We have indeed a * common sense' for the perception of 9) 
common qualities. I do not mean accidentally. It is there- ' 
fore not a particular sense, for in that case we should 

doctrine of AriBtoile that 'common properties' are cognized by the 
* Bensus communis,* in its own nature, and by the individual senses only 
per aceidena {De an. 425a 20, 25 ; 418a 9 ; 418a 24 ; De aensu, 437a 8). 
Biehl seems to have been influenced by the w /card ov/i^ptfK^ of 
425a 28 and its apparent contradiction of the present passage. There 
is, however, no contradiction, the od /card, k.t.X, referring to the 
function of the 'common sense,' while the jrard av/tfiefiriK^ refers to 
the function of the individual sense. 

1 We cognize the quality sweet by means of sight only per accideiM, 
We 6te a sweet thing t,g, when we see a grape with a given colour and 
contour, knowing by experience that the colour and contour are 
associated with a quality sweet to the taste. 



perceive in no other way than as just now described in 

10 the illustration of Clo^n. A sense, however, perceives 
accidentally the qualities that are peculiar to a different 
sense, not in their own nature but because of the 
unity of these qualities, as when two sense-qualities 

425 b apply to the same object, e.g, in the case of bile that it is 
both bitter and yellow. Now, it is not the function of 
either particular sense to say that both these qualities 
inhere in one thing and it is owing to this fact that error 
arises, when in the case of a yellow substance one opines 
it to be bile. One might ask why we are endowed with 

11 several senses and not with one only. Is it not that 
facts of sequence and coincidence, such as motion, magni- 
tude, and number, might the less escape us ? For if we 
possessed sight only, and this were limited to the percep- 
tion of whiteness, then all other distinctions would the 
more easily escape our knowledge, and because colour 
and magnitude are always coincident, they would appear 
to be identical In point of fact, however, since these 
common qualities are found in different sense-objects, it is 
evident that the several qualities themselves are different. 




But inasmuch as we perceive that we see and hear, we 
must have this consciousness of vision either by the 
instrument of sight or by some other faculty.^ The 
same faculty will then apply both to sight and to colour, 
the object of sight In this case, either we shall have two 
senses for the same thing, or a sense will be conscious of 
itself. Further, if there is another sense for the perception 
of sight, either we shall have an infinite regressus, or 
a given sense must finally be cognizant of itself, in 
which case one would better admit this in the instance 
of the original sense itself, ie. sight. Here, however, is 2 
a difficulty. For, if sensation by means of sight is vision, 
and colour or that which possesses colour is what we see, 
then the seeing faculty itself must first of all have colour 
in order to be seen. It is plain, therefore, that sensation 
by means of sight is not employed in a single meaning. 
For even when we do not see, it is by means of sight 
that we judge both of darkness and light, although not in 
the same way. Furthermore, the seeing subject is in a 

' This function of conscioasnen is performed by the ' seniuB oom* 

mania.' Gf. Introdaction, Chap. iv. 


100 Aristotle's psychology dianma 

3 certain sense saturated with colour, since each sentient 
organ receives into itself the sensible object without its 
matter. This explains the fact that when objects of 
sense have been removed, the sensations and images still 
persist in the sense-organ. 

4 The actualization of the object of sense and of the 
sense itself is one and the same process ; they are not, 
however, identical with each other in their essential 
nature.^ I mean, for instance, actual sound and actual 
hearing are not the same. For it is possible for one 
who has hearing not to hear, and for a sonorous body 

5 not to emit sound at every instant. When, however, 
that which has the potentiality of hearing and that 
which has the potentiality of sounding, actually hear 
and actually emit sound, at that moment the realized 
hearing and the realized sound are simultaneously 

426 a complete, and one would call them respectively the 

6 sensation of hearing and the act of sounding. If, 
then, movement, activity, and passivity are implied in 
the produced object, it must be that actual sound 
and hearing exist in a potential state. For creative and 
motive activity is given in antecedent passivity.* It 
is, therefore, not necessary for the moving principle 
to be itself in actual motion. For as action and 
passion find their expression in the object acted upon 
and not in the producing agent, so too the actualization 
of the sensible object and the sense-organ is expressed 

7 in the latter. The actualization of a sonorous body 
is sound or sounding ; the actualization of the 

^ The one is the condition of the other. 

' That is, in a potential condition or a condition to be acted npon. 


:nDg organ is audition or hearing. For hearing is 
and sound is twofold, and the same statement 
applies to other senses and sense-objects. In some 
instances the two have a distinct name, as e.ij. hearing 8 
and sounding ; in other instances one of the two is 
^meless. For the actualization of sight is called seeing, 
t the actualization of colour has no name ; the actual- 
ization of the organ of taste is called tasting, while the 
actualization of flavour is nameless. Inasmuch as 9 
the actualization of the sense-object and the sense-oi^an 
one and the same process, although the two things 
Ter in their essential nature, it is necessary that 
Iiearing and sound, in this sense, should be both either 
destroyed together or preserved together ; and the same 
applies to flavour and taste, and to the other sense- 
delates. This necessity does not, however, apply t-o 
sense-correlates in their potential signification. On 
contrary, the old naturalists were wrong here, 
:pposing, as they did, that neither white nor black has 
istence apart from sight, nor flavour apart from taste.' 

way they were right and iu another wrong. For 10 
ing to the fact that sense and sense-object have a 
Told signification, namely that of potentiality and 
.t of actuality, their dictum was applicable to the one 
ianing, but not to the other. They applied it, however, " 
things absolutely which are not predicated absolutely. 

'By the old lutanilistfl ire probkbly meant Empedocles, DemocrituB, 
' ftnd the Protagoreans (PbtlopoiinB ComineiU. ad 436a 22. Ed. Berl. 
Ac. p. 475). DemoctituB diBtlnguisheB between the primary and 
■econdarj (jqalitica of thinga, referring the latter {t.g. colour, Havoar, 
ito.) to the perceiving agent, and the (onner {t.g. weight, denii^, et«.} 
O the object. Cf. Theophrutas, De amaa. 6.1. 



If harmony is voice of a certain kind, and if voice 
and hearing are in a sense one and the same, and in 
another sense not one and the same, and if, further, 
11 harmony is a relation of parts, hearing must likewise 
be a relation of parts. It is for this reason ([».c because 
sensation is a kind of proportion]) that every excessive 
stimulus, whether acute or grave, disturbs hearing. In 
like manner the sense of taste is disturbed by exceBsive 
426* flavours, the sense of sight by extremely glaring or 
extremely faint colours, smell by excessive odours, 
13 whether cloying or acrid. Consequently, quahties are 
agreeable when, pure and unmixed, they are reduced to 
proportion, as e.g. the pungent, sweet, or saline, or in 
the domain of touch, the warm and cool. It is then 
that properties are pleasant. In general, the mixed, 
rather than the acute' or grave alone, is harmony. And 
sensation is proportion. Excessive stimidi either produce 
pain or pervert the organ- 
ic Every sense is directed to its own peculiar sense- 
object ; it is given in the sense-organ as such, and it 
distinguishes the different qualities in its appointed 
sense-object, as e.g. white and black in the case of sight, 
sweet and bitter in the case of taste. And the same 
can be said of other senses. Now inasmuch as we 
distinguish white, sweet, and every sense-quality by its 
relation to a particular sense, by what instrument do we 
15 perceive that these qualities differ from one another? We 
must do so by means of sensation, for they are sense- 
qualities. Is it not plain that the flesh is not the final 
oigan of sense ? For the judging subject would then 

' Acute uid grftvB are here QS»d generically for extreme*. 

it is 
^^BLn i: 


icessarily diatinguish an object by contact. Neither is 

possible by means of the distinct senses to judge that 

sweet is different I'rom white, but it is necessary that 

both these qualities be cognized by some one faculty; 

otherwise it would be like my perceiving one thing and 

you another, and ao proving that they are different. A i6 

single faculty nniat, therefore, say that they are different. 

For the sweet is actually different from the white. One 

and the same faculty, then, inuat affirm this. And as 

this faculty affirms, so do thought and perception agree. 

[t is clear that we cannot judge of distinct qualities by 

iflerent senses, and we can conclude from this that we 

mot judge of them at distinct intervals of time. For 

it is one and the same principle in us wlilch says that ■? 

le good is different from the bad. Further, it says that 
they are different and distinct at the moment when this 
affirmation is made. And wkm is not used here in an 
accidental sense, by which I mean : when, does not apply 
merely to the time of the affirmation, e.g. I say now that 
it is different, but it apphes also to the thing affirmed, I 
»y that it is different lum, i.e. the lime applies to the 
irtiou and thing coincidently. So the two elements li ] 
lere are inseparable, and are given in an indivisible 
loment of time. It is impossible for the same thing or 
indivisible entity to undergo opposite processes simul- 
taneously and in an indivisible moment of time. For if 
sweetness stimulates sensation or thought in one way, 
then bitter stimulates it in an opposite way and white- 427 a 
in some other way. Is, then, the judging principle' 
imething at once numerically indivisible and inseparable, 15 
The jndHtDg principle is the 'commun senso.' 

104 Aristotle's psychology deanima 

yet separable in the mode of its existence ? There is a 
sense, then, in which as divisible it perceives the divisible, 
and a sense in which as indivisible it perceives the indi- 
visible. For in its significant being it is divisible, but 
spatially and numerically it is indivisible. Or is this 

20 not possible ? Potentially, indeed, one and the same 
indivisible thing may contain opposite properties, but not 
in actuality ; in its realized self it is separate, and it is 
impossible for a thing to be at the same moment both 
black and white. So that it is not possible for even the 
forms of experience to undergo these opposites, if sensation 
and thought be such forms.^ Eather the case here is 
similar to what some call a point, which is divisible or 

21 indivisible, as one regards it in its single or dual nature.^ 
In so far as it is indivisible, the judging principle is one 
and coincident with perception ; in so far as it is divisible, 
it is not one, for it employs twice and simultaneously the 
same mark. In so far as it employs a terminal mark as 
two, it distinguishes two things, and these are separable 
for it as a separable faculty.^ In so far as it r^ards 
the point as one, it judges singly and coincidently with 

In this way, then, let us state our definition of the 
principle by virtue of which we say that animals are 
sentient beings. 

1 By the law of contradiction. Cf. MtU 10636 19 ; Col. 126 10. 

' That is, as a single thing, or as the beginning of one line and the 
end of another. 

'In so far as the mind looks at this single thing from two stand- 
points, as beginning and end, it acts in a way distinct from perception ; 
in so far as it looks at it as a single object, apart from relations, it coin- 
cides with the act of perception. 


Inasmuch as the soul is defined mainly by means of two 
attributes, namely by locomotion on the one hand and 
by thought, judgment, and sensation on the other, it is 
supposed that thought and reflexion are a kind of 
sensation (for in both instances the soul discriminates 
and cognizes some reality), and even the old writers 
tell us that reflexion and sensation are identical, as e.g. 
Empedocles, who said : '' Wisdom groweth in man in the 
face of a present object " ; and in another verse : " Hence 
is given unto them the power of reflecting ever and anon 
on diverse things " ; and the words of Homer have the 2 
same meaning : " Such is the mind." For all of these 
ancient writers regard thought as something somatic, like 
sensation, and believe that both in sensation and 
thought like is apprehended by like, as we said in the 
beginning of this treatise.^ They should at the same 3 
time have spoken of error, for to animals this is more 427 b 
natural than truth, and their souls pass most of their 
existence in error. According to this theory, as some 4 
hold, either all phenomena must be true or else error 

1 Dt, an. 4046 10 ff. 

106 Aristotle's psychology dsaioha 

consists in the contact of the unlike, for this is the 
opinion that is opposed to the cognition of like by like. 
Further, in this case error and knowledge of opposites 
seem to be identical. That sensation and reflexion, 
therefore, are not identical is evident For all animals 

5 share in the one, but few only in the other. Neither is 
thought,^ in which right and wrong are determined, 
i,e. right in the sense of practical judgment, scientific 
knowledge, and true opinion, and wrong in the sense of 
the opposite of these, — thought in this signification is 
not identical with sensation. For sensation when 
applied to its own peculiar objects is always true, and 
is inherent in all animals; but it is possible for discursive 
thought to be false, and it is found in no animal which 
is not also endowed with reason. Imagination, too, is 
different from sensation and discursive thought. At the 
same time, it is true that imagination is impossible without 
sensation, and conceptual thought, in turn, is impossible 

6 without imagination. That thought and conception, how- 
ever, are not one and the same is evident. For imagina- 
tion is under our control, and can be stimulated when we 
wish (for it is possible to call up before our eyes an 
imaginary object, as one employs images in the art of 
mnemonics). Conception, on the other hand, is not 

7 under our control. For it must be either false or true. 
Furthermore, when we conceive that something is terrible 

^ Noetv is used here as genos, of which ^p6rriffiSf itnan^foj, and 
96^ dXrjBiis are species. Thought is called ^p^rtais {prudence) when 
directed to a practical end, hrurHifnii (sdenlijic knowledge) when it is 
theoretical and the conclusion is demonstrable, 86^a d\ff$^ {right 
opinion) when the conclusion is not reached by scientific procedure or 
is not demonstrable and yet is true. 


or fearful, we have at once a corresponding feeling, and 
the same may be said of what inspires courage. But in 
the case of imc^nation we are in the same condition as 
if we were to place a terrible or a courage-inspiring 
object before us in a picture. In conception itself there 
are distinct forms, such as knowledge, opinion, reflexion, 
and their opposites, concerning whose difiTerent meanings 
we shall speak later. 

Since thinking differs from sense-perception, and in g 
one signification appears to be imagination and in another 
signification conception, we must proceed to the treat- 
ment of the latter, after we have defined imagination. 9 
If imagination means the power whereby what we call a 428 a 
phantasm is awakened in us, and if our use of language 
here is not merely metaphorical, then imagination is one 
of those faculties or mental forces in us by virtue of which 
we judge and are capable of truth and error. And these 
faculties include sensation, opinion, scientific knowledge, 
and reasoning. That imagination is not to be con- 
founded with sense-perception is plain from the following 10 
considerations. Sensation is either a mere power or a 
distinct act, like sight and seeing, but imagination is 
present when neither of these conditions is realized, viz. 
in the phantasms of dreams. Again, sensation is always 
present, but this is not true of imagination. If in reality 
it were identical with sensation, then all animals would 
have imagination. This does not seem to be the fact, as 
we find in the case of the ant, the bee, and the worm. 
Again, sensations are always true, while imaginations are n 
for the most part false. In the next place, we do not 
say when we are accurately observing a sense-object, that 

108 Aristotle's psychology dsamima 

we imagine it to be a man. We say this rather when we 

12 do not clearly perceive [and when the perception may 
be true or false], and as we said above, we see imaginary 
pictures even when our eyes are closed. But neither is 
imagination one of those faculties whose deliverances are 
always true, as e,g. scientific knowledge and reason. 
For imagination can also be false. It remains to be 
considered whether it is opinion, for opinion can be either 

13 true or false. Opinion, however, is followed by belief (for 
no man can have an opinion and not believe what he 
opines), and none of the lower animals possesses belief, 
although imagination is found in many of them. [Again, 
every opinion is followed by belief, as belief is followed 
by persuasion, and persuasion by reason. Now, some of 
the lower animals have imagination, but none of them 

14 have reason.] It is plain, then, that imagination is not 
opinion combined with sensation, nor mediated by sensa- 
tion, nor a complex of opinion and sensation, and, for 
the same reason, it is clear that opinion has for its 
object nothing else than what sensation has for its object. 
I mean e.g. that imagination is the complex of an opinion 
of whiteness and a sensation of whiteness, and not the 
complex of an opinion of goodness and a sensation of 

428^ whiteness. To imagine, therefore, is to opine what, 

15 strictly regarded, is a sense-object. Again, there are 
false appearances when we have correct conceptions, as, 
e.g. in the case of the sun which appears to be a foot in 
diameter, whereas we believe it to be larger than the 
inhabited earth. The consequence is that we must either 
have thrown aside our true opinion which we held, 
without the thing having changed and without any for- 


getfulness or change of conviction on our part ; or if one 
still holds it, it is necessary that the same opinion be both 
true and false. But an opinion has become false in a i6 
case where an object, without our knowing it, has 
changed. Imagination, then, is not one of these faculties 17 
nor a derivative of them. 

Since one thing when moved can communicate motion 
to another, and since imagination is held to be a form of 
motion which does not come into existence without 
sense-perception, but only in sentient creatures or in 
reference to objects to which sensation applies, and since 
motion is produced by the action of sense-perception, and 
this motion must be equal to the strength of the sensa- 
tion, one can affirm that the motion of imagination 
would never be possible without sensation nor could it 
take place in non-sentient creatures. Further, the one 
who experiences it can act and be acted upon in many 
ways, and one's experiences may be true or false. This 18 
truth or falsehood is due to the following causes. Sense- 
perception is true when it concerns its own peculiar 
objects; at any rate, there is involved in this case, the 
least possible amount of error. In the second place, sense- 
perception may concern the accidental, and here error 
begins to be possible. One is not mistaken in saying that 
a thing is white, but if one says the white object is this 
or that particular thing, error arises. In the third place, 19 
error applies to common properties and concomitants of 
the accidental, in which peculiar properties are involved. 
I mean e,g. motion and magnitude, which are accidental 
properties of sensible objects, and concerning which w( 
are especially liable to error in sense-perception. The 



motion set up by tbe activity of seosation will differ iu 
20 terms of ihe tiiree following forms of sense- perception. 
The first movement is when the senae-perceptiou continues 
present, and this ia true ; the other two may be ffdae 
whether the object is present or withdrawn, but are 
especially liable to error when the sense-object is 

If imagination contains nothing but the elements 

429" named and is what we have described it to be, it would 

be a movement stimulated by actualized sense-perceptioD. 

II Since sight is our principal sense, imagination ' has 

' The wonls ^irula ond ^ot »re derived from oognftte rooU [^r 
and ^F) onA (Kilxirflai aud fnurao-ja &re etymologicolly Bkln. Arutotla'a 
statement that ttie one is derii-ed from the other ia not strictly correct. 
It has been shown th&t imagination ia not olrSiiait (aenaation), nor voft 
(reason), nor irurHiiii (aoientiflo knowledge), oor 3ifa (opinion). It 
ortginKea, however, in the ittninis commnnin and ia a movement let up 
there by a past lensatioa. A aeaaation when past may leave on after- 
effect in the Beose-orgaa irhii;h (gain, nnleae «ome greater or craas- 
stimulua inbibita it, may pass to the heart (the organ of the 'oonunon 
lenae ') and there be revived u a pictorial image or phantasm, the real 
object being: no longer present. This revival of a seoHe-image is 
imagination or phantasy (^iTairCa), and the image thus reproduoed ia * 
phantasm [ipirTaaiia). f^ensation, therefore, is a prereqoiaite of im- 
agination, although the revival of the reaidusi image of aense is 
omaoaipaled from the Bctioo of the senie-organ iteelf. Aristotle dii- 
tingnishes imagioatioa from sensation : (I) imagination is a fniiDtioD of 
the interoal or 'common sense' {De nwni. ■WOa 10), sensation is a 
process of the external sense ; (2) imagination maybe setive in sleep, when 
tbe sensea are inactive, or when tbe eye is closed one may have visual 
imagination (428(i 16) ; (3) eenaatinns. as such, are Crae, while imagina- 
tions are in large part false ; (4) sensation is possessed by all snimala, 
imagination by certain ones only (428a 10). Again, imagination is 
distinct from reason (voOi) and scientific knowledge Unarl)nt)), for (1) 
both the latter proceed by necessary steps and ore consequently true, 
while imagination is sometimes true and sometimes false (128a IS) ; (2) 
the steps in rational or sciontifio knowledge are not in our control, they 
follow from inherent neoeasity, while the picture* of imagination kre 
arbitrary (12Ti> lil). Farther, imagination is ilistiuct from opiuiou 



derived its name from light, because sight is impossible 
without light. Because images persist and resemble 
aeDse-perceptioDs, auimals regulate their actions to a large 
I degree by imagiuation, some of tbem because they are 
' incapable of reason, as the lower brutes, others because 
rea<sou is sometimes veiled by passion, disease, or sleep, as 
is the ease amougat men. Concerning imagination, what its 
nature is aud what end it subserves, let the foregoing suffice. 

(Mfa) : (I) opinion is KcoonipaniBd hy 1>elief, which ii not trne of 
imagin&tian ; (2) we may have a currect opmiaD abonl n thing, but onr 
imsgiiukMou about the aanie thing ma.j he qoite at (arianoe with the 
opiuioD {tSSIi 2). Further, it is not u uombinatioii of opinion anil 
senaatiou ■■ held by Plato {Soph. 2G4b, irii^i^ii uirff^j-fiiii ml Sifjji), 
becauae opinian and imaginatioD may contradict, and conieqaentlj, in 
tiiia case, must exclude, each other. 

Wheu the image is recognised aa that o( on object perceived in the 
piut, with a conBciouineaa of time, the imagination IB tlien termed 
memory {ur^uv) "i"! the image is ttrrinbrfufia. If the roproduotion of 
the image a conHcionB and deliberate, the act ia recollection {irifir^it], 
Inaamnoh aa the latter act reqaires reflection, only man is endowed 
with it, although memory is shared by the hrutes {Dt mem. 45.30 6 ff). 

There U imother form of imagination which one ma; call the general- 
izing imagination, and which Aristotle regards as the wtorce of (lie 
fl that accompany conceptual tboaght He says there is no 
.bought without an image (403a 3, 431rE 16). Aa senaation is to the 
imagiuatioD, ao in the imaginatioD to thought (431a 14). Residual 
IB are, therefore, the intermediary links lietween sensation or 
perception and thought, ttegarded as after- sensation, imagina- 
tion ia called ^tarrmria uiaOTrni^ : regarded as the prereqoisite of 
thought, it is called ^wraula Xoyurriic^ {iSSb 29). Imaginatfon is a 
weak or spent Bensation (ab^i^n AtScr^, Jihet. 1370a 28) or in Hobbes' 
language a "decayed sensation." Cf. Preudenthal, Uehtr den Begriff 
da Worlta ^/arraala p. '24. 

The imagination in its reproductive (unction is the source of memory, 
recollection, and the asaociatioD of ideaa; in its productive or coo- 
itmotire function, it is the origin of fancies and distorted pictures in 
dreams, fever, and melancholia. Without it language would be im 
pOMible (420b 32), and it give« deameBB to conceptual thought by 
cloUting this in the schemata of sense (42T[i 16 ; 431F' 4 ; 432a !>}. 


Eegarding that part of the soul by virtue of which one 
knows and reflects, whether it be a distinct part or 
whether it be distinct only notionally and not really, we 
have now to consider what its differential mark is, and by 
what process thinking is exercised. If thinking is like 
sense-perception, it would be either a kind of impression 
made by the object of cognition or some analogous 

2 process. It must, then, be impassive and yet receptive 
of the form,^ and in its nature potentially like to the 
object of thought without being this object ; and as the 
sense-organ is related to the object of sense, in a similar 

3 way thought must be related to the object of thought. 
Season must, therefore, be unmixed, as Anaxagoras says, 
since it thinks everything, in order that it may rule, Lt, 
in order that it may know.^ It is the nature of thought 

^ Sensation is described by Aristotle as the receptivity of the form 
or idea of a sensible thing without its matter {Dt an, ii. 12, 424a 18, 

'This interpretation of Anaxagoras is regarded by Bamet (Early 
Oreek Pfiilos. p. 283 fr. 6 and 293, note) as unhistoricaL He thinks 
the power of Nous to ' rule * means only the power to move and direct 
(jcv/Sepyav). Aristotle himself gives precisely Burnet's interpretation 
of the Anaxagorean Nous in Fhys, 2566 25 (xcm^ectft dfoc^ l Plato, 



to preclude and restrain the element that is foreign aad 
adjacently seen. Its nature is, therefore, exclusively 4 
potentiality. What we call reason in the soul (by reason 
I mean the instrument by which the bouI thinks and forms 
conceptions) ia, prior to the exercise of thought, no reality 
at aU- It is, therefore, wrong to suppose that reason itself — ■ 
is mixed with the body. For in that case it would have 
certain qualitative distinctions such as warm or cold, or 
it would be a sort of instrument, Like a sense-organ. But 
in point of fact it ia nothing of the kind. Certain writers^ s 
have happily called the soul the place of ideas, only this 
description does not apply to the soul as a whole, but 
merely to the power of thought, and it applies to ideaa 
only in the sense of potentiality, and not of actuality.^ 

CnUylof, 413c), sod Bocording to De an. 4056 22 and 429A 23. he 
would geem b) have been anabte to Snd ftny eiiiBtemolagickl Die for 
thle Nous. The iDtecprototion oF Aristotle in the poiiMgB before 
UB can, howcvar, very well be a correol daduotion from the prioaiple 
of AD&xagorwi, viz. that in order to rule aad arrange all things be<t, 
the reason mast alaa know tH thinga, uid it U not unlikely that 
Anaxagoru even made explicit mention of thia ; it ii oerbuoij 
implied in the fragmaDta. " Noub is the gublleat ot all thing* KoA 
the purest [i.e. the least mixed], and it knows all and has all 
power" (fr, 123, Burnet p. 2S3). By virtue of its subtle nature, and 
\t» being unmixed with the eletnents (I am not concerned here with the 
moot question of its Inoorporeality), the Nous is able ta penetrate 
everywhere, and so haa the most far-seeing knowledge as well as moat 
wide- reaching power. Nous must then be unmixed and pore to be 
almighty and all-knowing, and consequently the commentary of Aris- 
totle seems a legitimate constmction to put upon Anaxagorae (of. 
Zaller, PhU. d. Or. Vol. L 4th ed. p. 8ST ; Trendelenburg, Dt an. 2nd 
ed. p. 385). In fact, it ivaa precisely the element of knowing that wa* 
the important factor in the Anaxagorean N~odb, as Orderer of the All. 

■ Plato and the Academy. 

* Potentially, reason ia that which becomes thought (there are no 
innate ideas) ; but the actual reason is identical with the actual 
Ight. and in thinking itn idoos thp reason thinks itself H^M 9). 



It is evident from the sense-orgtiD and from the nature 
of sensatiou, that the term impassivity is employed in a 

6 different nieBning in sensation and in thinking. For 
sense-perception cannot take place when the sense- 

429^ stimulus ia excessive, as one does not hear sound in the 
midst of loud noises, neither can one see nor smell in the 
midst of excessively bright colours and strong odours. On 
the other hand, when the mind thinks a very profound 
thought, it thinks not in a lesser but in a deeper 
degree minor details. For the power of sensation is not 
independent of the body, while the mind is separable. 

7 When reason becomes its several objects in the sense in 
which an actually learned man is said to be learned (and 
this takes place when he can exercise knowledge through 
his own agency), even then reason is in a certain sense 
potential, although this potentiality differs from that 
which preceded learning and discovery. In the latter 

s case, potentiality signifies the capacity of thinking itself. 
There is a difference between concrete mt^itade 
and the ultimate nature of magnitude, between water 
and the ultimate nature of water (the same distinction 
can be applied to other instances, though not to all, 
for in some cases they are identical). Concrete flesh 
and the ultimate nature of flesh one judges either by 
a different and distinct faculty or by the same faculty 
under dill'ering conditions. Flesh is not separate from 

9 matter, but like a snub-nose, it is a particular thing 
in a given something. By means of a sense-organ one 
discriminates heat and cold and those qualities of which 
flesh is a sort of register. On the other hand, reason 
judges of the essential nature of flesh either by a 


[ different and distinct faculty, or in the way in which 

I a bent line is related to itself when straigbtenod.' 
We refer the straight line as we do the snub-nose to 
abstract entities,* for they are both oaaociated with the 

I continuous. But the essential notion of a thing, if 
Btniightnesa and the straight line are different (and they 
are two things), is apprehended by a different power. 
The mind, then, judges in the two cases by means of 
a different power r>r by means of a power differently !■ 
conditioned. In a word, therefore, as there are things 

I abstracted from matter, so ther« are things that concern 
the reason. If the mind ia simple and impassive, and 
has nothing in common with anything else, as Anaz- 
agoras ' says, and if thinking means to be somehow i 

' The bent line represenU the concrete, (liatort«d thmgs of sense 
knd the itraight line the pure noticm, uitl the two things comapond, 
•pp*rei)tly, to the diitinctiun mode above between ri aapti ilriu uid 
rApi, etc. Cf. Kirehmann and Wallace ml loc. Teichmiiller'i explana- 
tion ((|uot«d by Wallace) of the bent line ai repreaenting reawlD, 
althougli ingeniouB, is not helpful hEre. 

'These conceptions belong to matheinatical notiooa and Ggnrea, and 
are abstract when contrasted with a material thing, but concrete when 
contrasted with the essential notion. Mathematical ideas (including 
' »nab-nose ' ai a figure) occupy a middle place in their ilegree of 
abstraction between the pure notion and a sense-object. The maths- 
matical and the sense-object both belong to the continuous or the 
extended in space {fiiri irwrxoOi). CI. Phj/t. IMa 10; Df an. 431b IS. 
MathemaUoal entities are ■«parab1e from matter only in logical coo- 
cepUon. Mttaph. 1026ci T ff. : 1061a 2S ff. 

'Anaiagoras gave no detailed accoiuit (as far as the fragments gt>) 
of the way In which we get our ideas of things, beyond the state- 
ment that the senses are too weak to discover Che ultimate nature of 
reality, and that we know the existence of the o/ukd^/icioi (as his 
succesHors called the original homogenenuB seeds or particle! of things) 
only by processes of reason. This latter by its subtle and pure nature 
is capable of peuetratiog everywhere {vid. note 2. p. 11*2) and making 
the finest distinctioDB. In his tbeoc; of sensation Anaisgoru says we 



impressed, one might ask, How will thought be possible ? 
For it is only in so far as there is something commou 
to two things that the one appears to act and the 
other to be acted upou, A further question might 
be raised, viz. whether the mind itself is the object of 
thought. If it is, mind will then either be found in 
other things, unless it is the object of thought in some 
way different from other objects, and unless the object 
of thought is a specific and single thing; else it will 
have a mixed composition which makes it like other 
II things, the object of thought. According to our former 
definition, ' to be affected in reference to a common 
element,' means that the mind is potentially the object of 
thought, though perhaps not actually so until thought takes 
place It must be that the case here is similar to that 
430" of the tablet on which nothing has been actually written. 
This is what takes place in the case of mind, and it is 
13 the object of thought as other things are. Where entities 
are without matter, the subject and object of thought 
are identical. Speculative thought and the thing specu- 
latively known are one and the samo. The reason why 
thought is not continuous must be investigated. On 
the other hand, when entities are material they are 
severally the object of thought only potentially ; mind 
is not au element in them (for reason is the potentiality 
of such objects in abstraction from their matter), whereas 
it is in the reason itself that the object of thought will 
be found. 

do not apprehead like by lihe ^Empedoclea), but unlike by unlika, t.g. 
beftt l>y mid, etc. Cf. ZeUer PhU. <t. Or. Vol. I. 4th ed. p. OOS. 


In the whole of nature there is on the one hand a 
material factor^ for every kind of thing (and this is 
what all things are in their potentiality), and another 
factor which is causative and productive of things, by 
virtue of its making all objects, as art stands related to 
the matter it employs. These distinctions must also 
hold good when applied to the souL Season is of such (a 
character that on the one hand it becomes all things, 
and on the other creates all things, in this respect 
resembling a property like light. For light in a certain 
sense converts potential into actual colours, and reason, in 
the present meaning, is separate, impassive, and unmixed, 
being in its essential nature an energizing force. Now, 
action is always higher than passion and causal force 
higher than matter. Actual knowledge is identical 3 ^ 
with its object Potential knowledge, on the other hand> 
pge -PTiflts i n t h e^nflmc hnfl^ "f^ ^ed ab a ululely ft does 

^ * Material factor ' does not neoeoarily mean a thing oonstitated of 

craM matter, bnt refers to the metaphyucal diatinotioii between ' form * 

and ' matter,' which in other terms are ' aotoality' and ' potentiality.' 

In this meaning sensations as containing the potentiality of ideas are 

their 'matter.' 


118 Aristotle's psychology deanima 

not 80 pre-exist. For mind does not at one moment 
think and at another not. In its separated state alone 
reason is what it is, immortal and eternal We have no 
memory of it, because this part of reason is impassive. 
The passive reason, on the other hand, is perishable, 
and without it there can be no thought^ 

* Vid, Introdaotion, Chap, viii., and 7%e ClauieeU Review, Vol. VI. 
(1892), pp. 298 ff. 


When thought is .applied to indivisible terms, error does 
not arise. Where error and truth are both found is just 
in the combination of thoughts into a sort of unit^. 
Empedocles^ e,g, says; "Wherefore the heads of many 
creatures sprang into life without necks," and later on 
by the attraction of Friendship they were joined to- 
gether. So, too, these disjoined ideas are combined 2 
together by the reason, as e,g, the ideas of the incom- 
mensurable and the diagonal. If the ideas refer to the 
past or to the future, the element of time is added in 430^ 
the mind and combined with the ideas. Error is always 
due to the combination. For even in the case where one 
might think the white not to be white, one has made 
the combination of the 'not-white.'^ It is further 
possible to apply disjunction to everything. It is not 3 
only possible for the statement ' Cleon is fair ' to be 
true or false, but this may be applied to the past or to 
the future. The unifying princii^e is in every case the 

1 Barnet, Early Ortek PhUo9ophy, pp. 226, 229. Ritter and PreU«r 
HuU. Phil. Or. p 140t». 

'Omit <irac> ^XetNcdr^ which Biehl adopts from Ood. T and Rdper's 
conjeotnrs againat the better reading of aU the other Codd. 




reason.' Since the simple or iDdivisible may be looked 
at from two standpoints, viz. either as potentiality or as 
actuality, there is nothing to prevent the mind &om 
thinking the indivisible when it thinks of extension 
(which in its actual state is indivisible), and when it 
thinks it in an indivisible moment of time. For 
divisibility and indivisibility apply to time just as they 

4 do to length. It is, therefore, impossible to say what 
the mind thinks in each half of a time-division. 
For the half does not exist, except in potentiality, if 
the division has not been made. But in the act of 
thinking each half separately, the mind divides the 
time also, and then the time corresponds in its division 
to the two lengths.* If, however, the mind thinks 
the object as a whole composed of two halves, it does 
this also with regard to time in its relation to the 

5 two halves. 

That which is not quantitatively hut only notionally 
indivisible, the mind thinks in an indivisible time and 
by an indivisible power of the aoul. It does this, how- 
ever, accidentally and not in so far as the factors of 
thought and time are divisible, but in so far as they 
are indivisible. And there is also in these cases an 
objective factor which is indivisible, although perhaps not 

6 a separate entity, that gives a unity to time and exten- 
sion. And this is likewise true of everything that is 
continuous, whether in time or space. The point and 
everything obtained by division, and whatever (like a 
point) is no longer divisible, are explicable in terms of 

' The ptinoiple thU combino or uoifiea temu into judgmenti. 
' And tbe single length ie then & unit and no longer a half. 


privation.^ Similar reasoning may be applied to other 
cases, as e.g. the way in which we know evil or black. 
For we know them somehow or other by means of their 
contraries. But the knowing mind must be these things 
potentially, and they iBust be rednoed to unity in the 
mind itself. If, however, in the case of any causal 7 
principle tfaer^ is no opposite, then it knows itself, and 
is in actuality and is separate. A predication, as e^. 
an affirmation, asserts something of something else, and 
is in every instance either true or false. This does not 
apply to the mind always, but when the mind asserts 
what a thing is in its essential nature and not what 
attaches to something as a predicate, then it is true. 
And just as sight is true when it concerns its own proper 
object, and on the other hand the opinion that a 
visible white object is or is not a man may not always 
be true, so it is with all immaterial entities. 

' As privation of extension. 


431a Actual knowledge is identical with its object Potential 
knowledge is earlier in time in the individual, but taken 
absolutely it is not earlier in time. For all becoming 
proceeds from actual being. /The sensible object appears 
to convert the potentially sensitive organ into an actually 
sensitive organ. For the sense-organ itself is not affected, 
and undergoes no change.' That is the reason why we 
2 have here to do with a form of motion different from 
motion in the ordinary sense. Motion was defined as a 
realization of the incomplete, but motion, absolutely 
regarded, is a different kind of activity, viz. the activity 
of the perfected thing. Mere sense-perception, then, is 
like a simple expression or a simple thought; when, 
however, the sensation is pleasant ^ or painful, and thus 
corresponds to affirmation or negation, the thing is 
pursued or avoided. To feel pleasure or pain signifies 
to experience an activity in a mean function of the 
sense-organ relative to good or bad as such. Avoidance 

1 When the simple term or thought ia converted into a judgment, it 
takes the form (inteUectuaUy) of affirmation or negation, and the form 
(in practice) of doing or avoiding. In the one case we have truth or 
error, and in the other right or wrong. 


BK. in. OH. vu. 



and pursuit in their actual natures are identical, and the 3 
appetitive power whereby we desire or pursue a thing isr 
not different from the power whereby we avoid a thing. 
They do not differ frt)m each other or from the sensitive; 
faculty. Only the expression of their being is different] 
Images are employed by the conceptual reason as sensed 
presentations are by the sentient faeulty. When the 
mind make8''an oflhrmation or negation touching the good 
or -ted; it avoids the one and pursues the other. The 
soul,- t h er efore , nevet thinks without the use of images. 4 
As the eir produces such or such an effect on the pupil 
of the eye, and the pupil in turn produces another effect 
(the same illustration may be applied to hearing), and 
yet the ultimate interpreter or medium of sensation is a 
single power whose being is expressed in several ways, 
([so it is with images^ in reference to thought.]) As to 
the faculty by which we discriminate sweet and warm, 
although the problem has been mentioned above, it 
must be again discussed as follows. There is some 
unitary principle, and this unitary principle has the 5 
character of an ultimate term. Its deliverances are 
reduced to unity by means of comparison and numerical 
statement, and are related to each other as the outward 
things are related to each other. The question as to 
how the mind judges like qualities, does not differ from 
the question as to how it judges opposite qualities such 


' As the air is a condition of sensation, so are images conditions of 
thought. The iUostration is not a very happy one, bat the meaning 
appears to be that as there is an anitary principle of sense which [ 
elaborates its varied materials into a whole, so there is an unitary 1 
principle of thought which reduces these images (ultimately drawn 
from sense) to the form of oonnectad concepts. 



6 as white and black. Let A. the objectively white, be 
related to B, the objectively black, as the idea C is 
related to the idea D, or it may be stated conversely. 
Now, if the ideas CD attach to a certain thing, they will 
be related to each other ([in the concept]) just as AB are 
related to each other, — they will form one and the same 
thing, though not identical in mode of being ; and the 
former combination (CD) is analogous to the latter 
(A6) '. The same reasoning holds in case one were 

431 i to apply A to a sweet object, and B to a white 

7 object. 

The reasoning mind thinks its ideas in the form of 
im^es; and as the mmd determines the objects it should 
pursue or avoid in terms of these images, even in the 
absence of sensation, so it is stimulated to action when 
occupied with them. For e.\ample, when one sees that a 
beacon is lighted, and observes by means of the ' common 
sense' that it is in motion,' one comprehends that an 
S enemy is near. Sometimes by means of the images or 
ideas in the soul the mind reasons as a seeing person, 
and takes thought for the future in terms of things before 
one's eyes. When the mind there in its world of images 
says that a thing is pleasant or painful, here in the world 
of things it pursues or avoids, — in a word, it acts. 
Apart from action the true and false belong to the same 
category as the good and bad. They differ, however, in 

' The illuatratiDD appears to meaii that just ta quftlities ue 
combined in a given thing anrl form ao unitac; object, ao subjeutively 
they form a single and unitary concept. They are iilenticil in lignifi- 
cance, though different in their mode of being. 

'Motion ii one of the ■roird aurSiri and as Buch is not iliscerned by 
any individual genee but only by the 'common leiue.' 



the absolute character of the one and the relative 
character of the other. ^ 

The mind thinks abstractions, as e^. when it thinks 9 
the snub-nosed, which in one sense is a snub-nose, and in 
another sense, if one thinks it actually, one would think 
it as a curvature without the flesh in which the curvature 10 
is found. So too with mathematical figures, though in 
actuality not separate from bodies, the mind thinks them 
as separated, when it thinks them. In a word the mind 
is the thing when actually thinking it.* Whether or 
not it is possible to think any abstraction when the mind 
itself is not separate from magnitude, must be investi- 
gated later. 

' The true and false are univenally valid, regarded merely from the 
standpoint of cognition, but when regarded in the light of wrong and 
right they are relative to the individnaL Or the passage may have 
another significance, viz. the notions of good and bad affect our wiUs and 
stimulate to action only when they are referred to particular objects. 
VicL Kirchmann, p. 183. 

* In the act of thinking, subject and object are identical ; the think- 
ing mind is the idea thought. 


Looking at the main features of what has been said of 
the soul, let us reiterate the statement that it is in a 
sense all reality. For everything, whether sensible or 
intelligible, is psychical ; intelligible objects are in a 
sense knowledge, and sensible realities are sensations. 
How this is possible remains to be investigated. Con- 

2 ceptual knowledge and sense-perception are each divided 
into two kinds, corresponding to their objects ; potential 
knowledge corresponding to potential objects, and actual 
to actual. The sensitive and conceptual powers of the 
soul are, potentially regarded, the objective things, viz. 
the intelligible and the sensible. The soul, then, must be 

3 either the things themselves or their form. It cannot, of 
course, be the things themselves. For a stone is not in 
the soul, but the form or idea of the stona Consequently, 

432a the soul is to be thought of as a hand; for a hand^ is the 
instrument of all instruments, and the reason is the form 
of all forms and sensation in the form of all sensible 

4 realities. Since, however, there is no object, as is supposed, 

' As the hand is the master instrument, so the sool is the master 
interpreter and redaoes all things to a significant form. 


BK. in. CH. vm. IDEAS AND IMAGES 127 

apart from sensible magnitudes,^ it follows that intelli- 
gible objects, — I mean abstractions, as we call them, on the 
one hand, and the qualities and conditions of the sensibles, 
on the other, — must be sought in the sense-forms. For 5 
this reason, also, it would be impossible for one to learn 
anything or understand anything without sense-perception, 
and when one contemplates a thing, one is forced to con- 
template it in conjunction with an internal image. These 
images are like sense-presentations, with the exception that • 
they are without matter. Imagination is difTerent from 6 
affirmation and negation; for the true and the false are the 
combination of ideas into a judgment' In what way are 
the primary ideas ^ to be distinguished from imagination ? 
Or is it true that these ^ ideas are not themselves 
images, yet they cannot be produced independently of 

' The world of magnitudes and objects in space are mediated to the 
imagination by means of sense-presentations {oM^j/MTa), and to thought 
by means of sense-representations or images {^atrrdr/MTa), 

'Images (^orrd^^ra) of the prodaotiye imagination, although they 
may correspond to no reaUty, yet are not, strictly speaking, either true 
or false. Truth and falsehood belong only to judgments or to an image 
when something is predicated of it. 

'The primary ideas {wpQra vo^j/iara) refer to our highest abstractions. 
Although these notions are not ^rrda/MTaf their derivation is dependent 
on such images. 

4 Read rath-a (Torstrik) instead of tAXXo. 


Since the soul of living beings is defined in terms of two 
powers, viz. the power of judgment (which is the function 
of thought) and the power of sensation on the one hand, 
and the power of locomotion on the other, let the above 
suffice for our treatment of sensation and thought, and 
let us now consider the moving principle and ask what 
part of the soul it may be. The further question arises 
whether it is an individual part of the soul and separate, 
either concretely or notionally, or whether it is the 
entire souL If it is only a part, we must ask whether 
it is a peculiar part and distinct from those usually 
described and already mentioned here, or whether it is 

2 one of these. There is a difficulty at the start con- 
cerning the sense in which we are to employ the term 

3 ' parts ' of the soul, and concerning their number. For 
in a certain way they seem to be innumerable, and not 
merely confined to those which certain writers distin- 
guish, viz. reason, will, and desire,^ and others classify 
as rational and irrational elements. For according to 
the differences by which they distinguish these parts, 

^ PUto, RqpMie 441a {Xtywruh^, 0v/Aoti9ii, HriBvfinriK^). 




^ere seem to be other parts that are even more distinct 
rom each other than these, concemlag which we have 
just now spoken, viz. the nutritive part, which is found 
even in plants as well as in all aaimals, and the sensitive 
part, which one could not easily classify either as irrational 
or as rational Again, the power of imagination, which is 4 
different in its mode of being from the others, appears to 433* 
be a distinct part, but in what particular it is identical with 
or different from the others, is very difficult to say, if one 
is to regard the parts of the soul as existing inde- 
pendently of one another. In addition to these, there is 
the desiderative part, which both notionally and function- 
ally might be supposed to differ from all the other 
parts. And yet it would be absurd to sever this from 5 
the others. For it is in the thinking element that 
LTolition arises, and in the irrational element we have 
;sion. But if the soul has three distinct 
, then the desiderative element must be iu all of 

Moreover, the question again comes up which we 6 
, just now, viz. what is the principle in animals 
that produces locomotion ? One might suppose that it 
is the generative and nutritive powers, found in all 
living things, that produce the motion involved in growth 
and decay common to them all. The subjects of inspira- 
tion and expiration, sleeping and waking, must be 
investigated later, for all of them present great diihculties. 
But regarding locomotion, we must inquii-e what it is 7 
that gives animals the power of progressive movement. 
It is evidently not the nutritive power, for progressive 
movement is always towards some end and accompanied 
either by some image or desire. For where there is no 



8 desire or revulaioD, there is uo motion, excepting where 
esternal force is used. Further, if motion were due to 
the nutritive power, plants would be capable of loco- 
motion and would have some organic member adapted to 
this motion. Soo, too, it cannot be the sensitive power 
that is the source of motion ; for there are many animals 
which have sensation and yet, throughout their existence. 

g are stationary and motionless. If, then, nature creates 
nothing in vain, neither does she omit anything that is 
necessary, save in cases of deformed or imperfect beings. 
And such animals as we have in mind are normal and not 
deformed. A test of perfection is the capacity to 
reproduce, to reach the prime of growth, and then decline. 
Consequently, sucli animals should also have organs of 

10 But neither is the thinking power nor what we call 
reason the cause of anitnal motion. For the contempla- 
tive power does not think upon what is to be carried 
into execution, neither has it anything to say touching 
what is to be avoided or pursued, whereas motion always 
belongs to that which pursues or avoids an object. On 

11 the contrary, when one contemplates anything, the mlud 
does not bid one pursue or avoid ; eg, the fearful or 
pleasant is often the subject of thought, but the feeling of 
fear is not su^ested ; the heart, however, is agitated, or 
if the feeling is pleasure, ^me other oi^an is stirred, 

433a More than this, even when the reason commands and 
intelligence tells us to avoid or to pursue a thing, motion 

' If tocomotioii wers t, funutioD ol the aeDsitiTC loul, th«w uumftli 
th»t are ondowed with aenBation, uid are nonnal, would not be 
■UtioiiBry, at some of thorn ore (cf. nnte 1, p. 171), bat would move. 


does not follow, but one acts according to one's desire, 
like an intemperate man. We observe, in general, that 12 
the man versed in medicine does not heal, because it is 
something other than science that has the power of 
acting according to the principles of science.^ Neither, 
again, is desire the dominating principle^ in this motion; 
for continent men, though filled with desire and appetite, 
do not do the things for which they lust; on the con- 
trary, they follow reason. 

^It 18 not science, but natare, the principles and laws of whose 
operation are formulated by science, that heals. 

^ Neither desire nor reason taken alone is the principle of action in 
men, but the combination of these two. Of. 4«S3a 23. 


There are two powers in the soul which appear to be 
moving forces— desire and reason, if one classifies imagina- 
tion as a kind of reason. For many creatures follow 
their imaginations contrary to rational knowledge, and in 
animals other than man it is not thought nor rational 
procedure that determines action, but imagination. Conse- 

2 quently, both of these, reason and desire, can produce 
locomotion — I mean here the reason that considers ends 
and is concerned with conduct^ It differs from the 
theoretical reason in having a moral end. Every desire 

3 aims at something. It is the final end that is the initial 
cause in conduct.' So that it is reasonable to r^ard 
these two principles, viz. desire and practical reason, as 
motor forces. For the object of desire stimulates us, and 
through it reason stimulates us, because the object of 
desire is the main thing in the practical reason. Imagina- 
tion, too, when it stimulates us to action, does not do so 
independently of desire. The one single moving force is 

>Thii is the epitactio reason (^p^ny^it HriroKTurn of the Ethics 
{Eth. nic, vL 10, 2). The theoreticsl reason deab with necessary tmth, 
while the praotioal or epitaetic reason deals with the contingent or 
what is matter of choice. 

* The end of action is motive or starting-point. 



the object of desire. For even if there were two moving 
powers, reason and desire, still they would produce 
movement in accordance with somQ common idea. As a 4 
matter of fact, however, reason does not appear to produce 
movement independently of desire. For volition is a form 
of desire, and when one is prompted to action in accord- 
ance with reason, the action follows also in accordance 
with volition. But desire prompts actions in violation of 
reason. For appetite is a sort of desire. Reason, then, 
is in every case right, but desire and imagination may 
be right or wrong. It is, therefore, always the object of 5 
desire that excites action, and this is either the good or 
the apparent good — yet not every good, but only the 
good in conduct, and this practical good admits of varia- 

Evidently the psychical power which excites to action 
has the nature of desire, as we call it. In analysing 6 
the elements of the soul, if one analyses and distinguishes 433^ 
them in terms of powers, they become very numerous, as 
€.g. the nutritive, sensitive, rational, deliberative, and 
desiderative. For these differ from each other more 
than do the desiderative and spirited elements. Although 
desires arise which are opposed to each other, as is the 7 
case when reason and appetite are opposed, it happens 
only in creatures endowed with a sense of time. (For 
reason, on account of the future, bids us resist, while 
desire regards the present ; the momentarily pleasant 
appears to it as the absolutely pleasant and the absolutely 
good, because it does not see the future). The moving 
principle, which is the desiderative faculty as such, is 
specifically one, though numerically several motive forces 

134 Aristotle's psychology dbanima 

may be inclnded in it. The main element here is the 
object of desire (for this by being the object of thought or 
imagination excites movement, while it is itself unmoved). 

8 There are, then, three terms to consider here, first the motor 
power, secondly the instrument of motion, and thirdly 
the object set in motion. The motor power is twofold : 
on the one hand, it is an unmoved element, and on the 
other, a moving and moved element. The unmoved 
element is the good to be done ; the moving and moved 
element is the desiderative faculty (for the desiderative 
faculty in so far as it desires is moved, and desire in 
process of realization is a form of motion); the object 
which is set in motion is the animal. The instrument 
by which desire effects motion, is of course the body, and 
consequently it must be investigated where we have to 

9 do with functions which are common to the body and the 
soul.^ One may, however, say summarily here that 
motion is organic in those cases where beginning and end 
are one, as e,g. in a joint. For here the convex and 
concave are beginning and end. Therefore the one is at 
rest and the other in motion, and while they are notion - 
ally distinct, they are concretely inseparable. Everything 

ID is set in motion by push or pull, and there must be con- 
sequently, a fixed point, as the centre in a circle, and 
this is the initial point of motion.^ In a word, then, as 
we said before, an animal in so far as it is capable of 

^The reference \b probably to the Parva NtUuraUa. Cf. 2<eller, 
Aristotle f Elng. tr. vol. i. p. 89 ; Freudentbal in Rhtin, Mtueum, 
N.F., Bd. 24 (1869), p. 82; Rose De Aristot. lUyrwrum ord. ef 
cmet. p. 183. 

' Ab in the illnstration of the socket- joint and the circle, there is a 
part at rest from which motion prooeeda and a part in motion. 


desire is capable of self-movement Desire, however, is 
not found apart from imagination, and all imagination is 
either rational or sensitive in origin, and the lower 
animals share in it. 

Analogously, the reason is not itself in movement but is that from 
which movement proceeds. The attractive thing on the one hand, and 
the commanding reason or desiring mind on the other, constitute the 
push and pull in animal life. 


We must inquire also into the nature of the moving 
principle in those imperfect animals which possess only 
434 tf the sense of touch. Is it possible for them to have 
imagination or desire ? They appear to feel pleasure and 
pain, and if these are felt they must necessarily have 
desire also. But how could they have imagination ? Or 
are we to say that just as their movements are indefinite, 

2 so too this power is possessed by them, only it is in- 
definitely developed. Imagination derived from sensation 
is, as we said before, found in the lower animals, but 
deliberative imagination is found only in those animals 
which are endowed with reason. For whether one shall 
do this or that is, of course, a matter of deliberation, and 
there must be some single instrument of measurement at 
hand (for it is the greater good that is to be pursued), and 

3 so the mind is able to make a single representation out 

of several images. The ground for supposing that 

animals do not have opinion is that they do not have the 

faculty for drawing rational conclusions, and opinion 

involves this. Consequently, their desire lacks the 

deliberative quality. Sometimes the desire overpowers 



the deliberative element in man and excites to action. 
At other times the will overpowers the desire, and again, 
like a ball tossed to and fro, one desire overpowers 
another, as in the case of intemperance. In the workings 
of nature the higher element always has the greater 
authority and is the moving power. There are, then, 
three forms of movement.^ The faculty of conceptual 4 
thought is not moved, but remains at rest. Since we 
have two principles in conduct, on the one hand the 
general conception^ and notion, and on the other hand 
the particular notion (of which the one says a man of 
such and such a kind shall act in such a way, and 
the other that this particular man — and I am that 
particular man — shall act in a given way), it is the latter 
notion that incites to action, but the general one does 
not Or both of them combined may lead to action, 
although the general notion is quiescent, and the par- 
ticular one active. 

^ There is (1) the command iasning from the unmoved reason, which 
acts on desire in a manner analogons to motion in the form of ' pnsh ' ; 
(2) when an object stirs the desire and through the desire the reason is 
awakened, the case is then analogons to motion in the form of 
'attraction' or 'puU'; (3) the completed process terminates in an 
act of bodily or physical movement. 

*Cf. Eth. nic vii. 3, 6, 1147a MO. 


Every living thing must have a nutritive soul in order 
that it may live and continue to live from birth until 
death. What has been bom must grow, reach its 
complete development and decline, and this is impossible 
without food. A nutritive power must, therefore, be 
given to everything that grows and dies ; but sensation 

2 is not necessary to all living things.^ Whatever has a 
simple body cannot be endowed with the sense of touch 
(neither is animal life possible without touch), and 
whatever is incapable of interpreting the forms of things 
without their matter is also incapable of touch. An 
animal must have sensation, if it is true that nature 
creates nothing in vain. For everything in the natural 
world exists for a purpose, or is the condition of some- 

3 thing that exists for a purpose. If, then, a body which 
is endowed with the power of movement were deprived 
of sensation, it would perish and would not attain the 

434* end for which nature strives. For how will it nourish 
itself? Amongst organisms fixed to one spot, a source 
of food is provided for them from which they naturally 

^ Vegetable life exiita only in the lowest or nutritive form. 


grow. It is, however, impossible for a body that is not 
stationary, and is produced by generation, to have life 
and a thinking mind, and yet not have sensation. No 
more is this possible in bodies that are not produced by 
generation.^ For to what end will they lack sensation ? 4 
It must be because such lack will be better either for 
their soul or body. But neither is true. For the one 
will thereby think none the better, nor the other last 
any the longer. Consequently, no moving body has a 
soul that is unendowed with sensation. K, however, the 
body is endowed with sensation, it must be either single 
or mixed. Thejormer is impossible; for in that case^ s 
it could not have touch, and touch is necessary. That is 
clear from the following grounds. Since every living 
creature is an animated body, and every body is tangible, 
and tangible is that which is sensed by means of touch, 
it follows necessarily that the animal body must be 
capable of the sensation of touch, if the animal is to 6 
persist in life. The other senses, such as smell, sight, 
and hearing, perceive through other media than the 
tangible body. If, however, an animal on being touched 
were to experience no sensation, it would have no power 
to avoid certain things and pursue others. And if this 
were the case, the animal could not survive. Therefore, 
taste is a kind of touch, for it is concerned with food, 
and food is a tangible body. Sound, colour, and smell, on 7 
the other hand, furnish no nutriment and do not con- 
tribute to growth and decay. Consequently, taste must 

^ £yen the eternal and anbegotten bodies (stars) have the power of 
sensation. Cf . Dt Codo, 285a 29, 2926 2. 

' Toach implies the daaUty of perceiying soul and tangible body. 



be a sort of touch, because it is a sense that concerns a 
tangible and nutritive object. Both of these senses 
([touch and taste]) are necessary to everj animal, and it is 
evident that no animal can exist without touch. The 

8 Other senses exist for the safee of higher well-being ' and 
are not found indiscriminately in animal species, but only 
in certain of them, viz. in such as are capable of pro- 
gressive motion, and here they are necessary. For if 
such an animal is to survive it must not only apprehend 
an object by touching it, but must be able to do this 
at a distance. This result would be attained if the 
animal were capable of sensation through a medium, 
and the medium were impressed and set in motion by 

9 the sensible object, and if the sense-organ were in tarn 
stimulated by the medium. Just as a body moving in 
space causes a transfer of energy up to a certain point, 
and the propelling body causes another body to become 
propulsive, and through the mediate term motion is 
continued; and as the initial agent moves and exerts 
propulsion without being itself propelled, while the last 
body in the series suifera propulsion without exerting it 
and the intermediate bodies (of which there may be many), 

435« both suffer and exert it; so it is also with the process 
of change ([in sensation]), excepting that here change may 
take place while the object continues on a single spot. 
For example, when one dips an object in wax, movement 
of the wax takes place up to the point that immersion 
has taken place. A stone, however, would not be moved 

' Certain crentnra ue enilowed merely witb fitnera for life, while 
the endowment ot others fits them for ncsthetic and mor&l life (iraXoii 
fwtna. ^r), Eth. Jik. 1143a 15, 1170a 16, llSOa 10; mf <S Ih», Dc oh. 
435b 21; Dt»mmi31a\. 


in this way at all, while water would be moved more lo 
than wax. The most mobile element, both in its power 
to receive and communicate motion, is the air, provided 
it is confined and is a unit. Concerning the phenomenon 
of the reflection of light, then, it is better to suppose that 
the air, in so far as it is a continuous mass (and this is the 
case upon every smooth surfsu^), becomes charged with 
form and colour, rather than that the visual image afber it 
has once issued from the eye is reflected back to the 
eye.^ Consequently, the air reacting on the eye stimu- 
lates it, as if the impress in the wax were to penetrate 
through to its opposite extremity.' 

^The reference is to Empedoolee, who beUeved there wm a dual 
efflux or emanation from the eye and from the object (of. Flatoe Mewm 
76g ffl, Ariitot Dt 9enau 438a 1 ff.) and to Plato (IVmoetw, 46o). 

'That is, the vianal image is supposed to penetrate through the 
mass of air, as it were, to the opposite side and so pass into the seeing 
organ, just as one might conceiTe the seal with its impress piercing 
entirely through the mass of wax into something capable of receiving it 
on the remote side. 


Evidently an animal body cannot be simple. I mean that 
it cannot e,g. consist simply of the element of fire or 
air. For without touch one cannot have any other 
sensation. Every body endowed with soul has the 
capacity of touch, as we have already said. All the 
other elements, excepting earth, might become organs of 
sensation, but all of them produce sensation by the 

2 instrument of intermediary bodies. Touch, on the con- 
trary, appears to act by immediate contact with bodies, 
and hence its name, and although the other sense-organs 
effect sensation by means of contact, yet the contact is 
indirect and mediated ; whereas touch is the only sense 
that acts by direct contact. So then no animal body 
can be constituted exclusively out of such elements ([as 
are fitted for mediate perception]), neither can it be 

3 constituted exclusively out of earth. For touch is, as it 
were, the mediator of all tangible things, and the sense- 
organ is capable of receiving not only all the various 
qualities that attach to earth, but also the hot and cold 
and all other tactual distinctions. Therefore we have 

no sensation in our bones, hair, and other such parts, 


BK. in. CH. xin. SENSE OF TOUCH 143 

because they are constituted out of the element of earth. 
For this reason also plants have no sensation, because 435^ 
thej are composed of earth. Without touch there can 4 
be no other sensation, but the organ of touch is not 
composed exclusively of earth nor of any other single 
element. It is plain, then, that this is the only sense, 
the deprivation of which necessitates the death of 
animals. For neither is it possible for anything that 
is not an animal to have this sense, nor is il 'viecessary 
for anything that is an animal to have any sense beyond 5 
it. Therefore, other sense-qualities, such as colour, sound, 
and smell, do not by their excess destroy an animal; 
they only destroy the sense-organ, except in some acci- 
dental case, as where a push or blow accompanies the 
sound, and when other objects are set in motion by 
sights and smells which, by their contact, work destruc- 
tion.^ Flavour, in so far as it is conjoined with a 6 
tactual nature,^ works destruction by virtue of this 
latter. But excess in tangible qualities such as heat, 
cold, or hardness, destroys the animal. For the excess 
of every sensible quality destroys the sense-organ, so 
that the tangible destroys the tactual sense, and it is 
in terms of this that life is defined. For it has been 
demonstrated that without the sense of touch a living 
creature is an impossibility. Consequently, excess of 7 
tangible impressions not only destroys the sense-organ, 
but also the animal itself, because this sense is the sole 
requisite to animal life. An animal possesses the other 

^ SimpliciuB {ad he,) thinks that lightning is meant here. 

'Aristotle woold appear to refer death by poison to its tactual 


senses, as we have said/ not for the sake of life but of 
a higher life. It has sight, e.g. in order that it may 
see, since it lives in a medium of water, or air, or, in 
a word, in a diaphanous medium, and it has taste, because 
of the distinctions of pleasant and unpleasant, and in 
order that it may detect these qualities in its food and 
so desire it and be moved to obtain it. It possesses 
hearing in order that information may be communicated 
to it, and a tongue in order that it may communicate 
information to others. 

1 Cf . De an. 4346 24. 




Now that we have treated of the soul in its essential 436 a 
nature and of the faculties that belong to it, part by part, 
our next duty is to investigate the subject of living 
creatures and everything that has life, to determine what 

' The following opuscules of mixed physiological and psychological 
content are never cited by Aristotle -under a general title, but always 
referred to separately. They were given the title Parva NtUundia by 
the scholastics, but even the learned Leonicus apparently does not know 
by whom {CcmmnfU. in Parva Naiw, foL 1530, p. 11), and Simon is 
only able to say " denominalio a Latinia inventa egt" {Comm. in libr, 
de senau, 1566, p. 1). The designation is used by Egidio Colonna (of. 
Bhein, Mttaeum, vol. 24, 1869, p. 81), who was a pupil of Thomas 
Aquinas, and we may assume that the title came into existence about 
the time of Thomas, when great interest was taken in the interpretation 
of the Aristotelian writings, although Freudenthal was unable to find it 
either in Albertus Magnus or in Thomas. The tractates discuss, in the 
main, the organic functions of animal bodies, and form at once a con- 
tinuation and supplement to the De anima and an introduction to the 
treatise On the Parts of Animals, They form thus a transition from 
Psychology to Zoology. In content they are mainly biological and physio- 
logical, concerned chiefly with the physiology of the senses. They 
supplement the Dt ammain the foUowingparticulars: In the Dt anima the 
soul is regarded as the principle of organic life, which is manifested in 
the forms of cognition and physical vitality. The detailed consideration of 
the relation between these two things is left for the Parva Naluralia ; 
K 145 



functioDS are specific ' and what functions are general. Let 
us then take what has already been said touching the 
Boul for our basis, and as we proceed to the remaining 
inquiries let what is flrat by nature^ be first in our dia- 

a cussion. The most important vital phenomena, whether 
one regards the specific or general attributes of animals, 
are those which are the joint concern of soul and body,* 
such as sensation, memory,* anger, desire, and impulse in 
general, and, one may add, pleasure and pain. These are 

3 experienced by almost all animals. In addition to these, 
however, there are other attributes which are common to 
nil animals that share in life, and others still that belong 
only to certain animals. The most important of the 
former class may be enumerated in four pairs, viz., 
sleeping and waking, youth and old age, inspiration and 
expiration, life" and death. We must study the nature 

further, the nature of memory, the associatiau of ideas, and the Bobject nf 
dreams, aretreuted almost exclusively to the opuscules. The brief accouDts 
of ' raiiiimoii senie,' pleaauro aad pain, and motioo in the Di animatrt 
■applemeutod here. Further, auch biological conitderationB aa the con- 
ditioDi, disturbancee, and duration of organic lite were scarcely notived 
in the Dt anima, but receive detiiled treatment in the tractates On 
Tov/h and Old A ge. Lift avd Death, and On Rapiralwm. 

' RenaoQ and RBcoUection r.g. are ipeoifio fnnctiona, while nutrition 
and growth are geaeral and common to all living orgaaiama. 

* By this is meant the elemental f anctlona connected with the life of 
the body (jco(»4 riji itux?) «aJ toC ffiifuiTDt /jrya), on which depend nutri- 
tion and reprodnction, aleeping and waking, etc. 

' Dt on. 4336 19, 20. 

* Memory [lirfiitii) but not recollection (dvl^nio-it), which jnvolvca 
reflection, aod ia peculiar to man. 

' To these four pairs of biological phenomena ia added a fifth below— 
health aud disease. Youth and old age, life and death are treated in 
one opnsaule, aleepbg and waking in another, inspiration and expiration 
in another, while the subject of health and disease was either not 
treated at all, or the treatise has been lost. No such treatise waa 
known to AlEiaiider Aphrodisiensis fComnaH. wi 'i36a 17). 


of each of these phenomena and the causes of its occur- 
rence. The investigation, too, of the ultimate principles 
of health and disease is the province of the naturalist; for 4 
neither health nor disease can apply to creatures when 
deprived of life. And so it happens, as I think, that 
most natural philosophers and those physicians who have 
a more philosophical understanding of their science, con- 
clude in the one case with the investigation of medicine, 
and in the other b^n their practice with deductions 436^ 
from the laws of nature and their application to medi- 
cine.^ The above-mentioned phenomena are evidently 5 
the common property of soul and body. For they are 
all conjoined with sensation or are mediated by it. Some 
of them are modifications of sensation or persistent condi- 
tions of it, others are protective or preservative of 
sensation, while others still are destructive and negative. 
That sensation is mediated by the body to the soul is plain 
both with and without the use of rational proof. How- 
ever, regarding the essential nature of sense-perception, 
and the reason why animals are endowed with it, we have 6 
already stated our views in the treatise (hi (he Soui.^ 
Every animal, in so far as it is a living creature, must 
have sensation. For it is in terms of this that we 
distinguish between animal and non-animaL Touch and 7 
taste must belong to all animals individually, touch 
for reasons given in the treatise On the Sovl? and 
taste on account of food. For it is by taste that animals 

^Gf. 4S0& 25, where the tractate on Respiration doees with an 
almost verbatim repetition of this statement. 

'In the Dt an, the purpose of sensation is described as two-fold, 
(1) the survival of the animal, (2) the ends of higher living (cf. 420^ 
20ff., 4346 22ff.). 



iliacriminate between agreeable and disagreeable in foods, 
and so reject the one and take the other; in a word 
flavour^ is an aSection that belongs to the nutritive 

s 30ul. Sensations that are excited by external objects, 
such as smell, hearing, and vision, are found in animals 
capable of locomotioD, and are given to all of them 
for the sake of their preservation, in order that they may 
scent their food and pursue it, and Hee from what is 
harmful and destructive. Id the case of animals endowed 
j7fl with intelligence, they are given for the sake of higher 
well-being. For these sense-perceptions convey to ua 
various distinctions, out of which the knowledge of intel- 

9 lectnal and moral concepts is built up. Amongst the 
senses, vision is the most important, both in itself and for 
the necessities of life ; on the other hand, for the uses of 
reason, and accidentally, hearing is the most important* 

10 The power of vision informs ue of many and various dia- 
linctions, because all bodies are suffused with colour, so 
that by means of this sense more than by any other we 
perceive the common properties of objects (by common 
properties I mean form, magnitude, motion, number). 
Hearing, on the other hand, informs ua merely of dis- 
tinctions in sound, and iQ some instances of distinctions in 

' That ii, flavonr at > property of food aQeclB the proceas of growth 
or the nutritive boqL Toach is the lowest or most fuDilameiit>l 
sense, ood taste is & form of touch mediated by the tongue. Tb«« two 
serve the primary or towast ends of life. Sight and hearing sarvs the 
higher or more iutelieotuai aeedn. 

'Although sight coQveyi to us the greatest number of impreasions 
touching the outaide worlil. Aristotle constden htiariiig the moat 
important of the senses intelleotaaUy, because it mediates oral instruc- 
tion. This Is oalled per accideru, because per >e the hearing mediates 
only sound, and it is auuidental to the function of hearing that thii 
sound shoold be siguidcant or have meaning. 



articulate voice. Indirectly, however, hearing contributes u 
the greatest share to our intellectual life. For it is the 
spoken and heard word that is the source of knowledge, 
and hearing is the source not in itself but accidentally. 
Language is composed of words, and every word is a 
symboL This explains the fact that in cases where men 12 
are deprived of one or the other of these senses from 
birth, the blind are more intelligent than the deaf and 

^This is no doubt correct, owing to the advantage the blind have 
over the deaf and dnmb in the nee of language. This advantage htm 
been greatly modified, of course, by the development of linguistic 
instruction for the deaf and dumb. The necessity of language for 
thought is a stlU unsettled question. Cf. James, PrineipUa of 
Psychology, VoL I. p. 269, who considers language, in its ordinary 
meaning, unnecessary for thought. Sully ( TTte Human Mind, VoL L 
p. 420), on the other hand, says : "It seems safe, therefore, to conclude 
that apart from verbal or other general signs the full consciousness of 
generality does not arise." Romanes {Mental Evolution in Man, p. 149): 
" These imfortunate chUdren [i.e. the deaf and dumb who are never 
taught finger-language] grow up in a state of intdlectual isolation, 
which is almost as complete as that of any of the lower animals." 


Wb have already treated of the function of the several 
special sensea Writers now-a-days attempt to correlate 
the senses with the physical elements ^ as found in the 
bodily members in which the sense-organs have their 
natural development With the fifth sense they are 
hard pressed, not finding it easy to pair five senses with 

2 four elements. All of them agree in r^arding vision as 
connected with fire, on account of a certain phenomenon 
whose nature they misunderstand : viz. when the eye is 
pressed and moved it seems to scintillate.^ But this 
takes place in the dark or when the eyelids are shut, in 
which case darkness is produced. And there is also 

3 another difficulty here. For if it is impossible for a 
perceiving and seeing subject to be unconscious of a seen 
object, then the eye must necessarily see itself. Why, 
then, does this not take place when the eye is at rest ? 
The explanation of this phenomenon, as well as the 
solution of the entire difficulty and of the apparent fact 
that vision is fire, is to be found in the following con- 

^ Empedocles, AlcmaeoD, Demooritas, Plato. 

'Pressare on the optio nerve, of which Aristotle knew nothing, 
stimalfttes the teuMtion of light. 



siderations. It is the nattire of smooth surfaces to shme 4 
in the darkness, although they produce no light ; now we 
observe that the dark central portion of the eye has a 437 ^ 
smooth surface. This becomes apparent when the eye is 
moved, because the single organ is thereby made double^ 
an effect which is produced by the rapidity of the motion. 
In this way the seeing organ and the seen object appear 5 
to be different^ For the same reason, also, this effect 
fails to be produced, when the motion is not rapid and 
does not take place in the dark.^ For it is in a medium 
of darkness that a smooth surface naturally shines, as we 
see in the case of the heads of certain fishes ^ and in the 
juice of the cuttle-fish. The consequence is that when the 
eye is moved slowly, the seeing organ and seen object do 
not appear to be at once unitary and dual. When, on 6 
the other hand, the movement is rapid the eye sees itself, 
as in the reflection of a mirror. Now, if vision were fire, 
as Empedocles declares and as we read in the TimaetLS* 
and if seeing resulted from the passage of light out of the 
eye as from a lamp, the question arises : Why is it that 7 
we do not see in the dark also ? To say, as the 
Timaevs^ does, that the light when it passes out from 
the eye is extinguished in the darkness, is a totally empty 
assertion. For what is meant by an extinction of light ? 
The warm and the dry, it is true, are nullified by the 
moist and the cold, as one sees in the case of a coal fire 

'That is, the seeing eye, which according to Empedocles is fire, 
appears to be seen and so to be different from the eye itself. 

' Because the smooth surface shines only in the dark. 

»Cf. Deam 419o6. 

« Timaeus, 42 b, 43 a ff. ; Meno 76c. 

^ Timaeua, 45 b ; cf. also TheaeUtua 166a 

152 Aristotle's psychology Disnreir 

8 or a flame, but neither of these has anything to do with 
light. If, however, they ^ are attributes of light but are 
concealed from us owing to their subtle presence, then 
light ought to be extinguished in the day during rain, and 
darkness should increase in frosty weather. Flame and 
ignited bodies are so affected, but nothing of the sort takes 

9 place in the case of light Empedocles appears to hold 
the view that vision results from the eye's radiating light, 
as we said before. His own words, at any rate, are as 
follows * : 

** As a man taking thought for his joumej 
A lantern prepares, whose flame flashes light 
Through the blustering night, as he passes. 
And shutters he fastens, defence from winds, 
To scatter the breath of the blowing blasts. 
While the light pierces through, by its fineness. 
And gleams over the threshold unfailing ; 
So, of old,' fire elemental was fixed 
438 a In membranes, and suffused * the round pupil. 

Held in thin tissues, a check to the water. 
While the fire pierces through, by its fineness." 

10 Sometimes he gives the above explanation of vision, 
and at other times he explains it by means of emanations 
from visible objects.^ 

^ The warm and the dry. 

*Cf. Burnet, Early Qrtek Philosophy, p. 231. 

' Instead of rb r* read rfn\ 

* Instead of Xox'ii^o read ix'^<faTo, 

'Each of these parts represents only half of the Empedoolean 
theory of perception. Light emanates from the fire in the eye, as from 
a lantern, and effluenoes come from sensible objects. These efflaences 
enter into the pores or passages of the eye, and in proportion as these 
effluxes are fine or crass, they enter into the larger or narrower 
passages. The fire is in the interior of the eye, and between this and 
the outer covering is a mass of water held by a fine net. The fire in 


Democritus says that vision is due to water, and in 
this he is right; but he is wrong in thinking that it 
consists in reflection. For reflection is produced because 
the eye is a smooth surface; vision, however, does not 
take place in this smooth surface but in the seeing 
subject. Now, the condition to which he refers is only a 
reflection of light. He has, however, as I think, no clear 
idea whatever concerning the general nature of images n 
and reflection. It is also strange that it never occurs to 
him to raise the question why it is that the eye 
alone sees, while no other object in which images are 
reflected, has vision. His statement that vision partakes 
of the nature of water, is true ; but vision is not due to 
the fact that the eye is water, but to the fact that it is 
transparent, which characteristic it has also in common 
with the air. Water, however, is easier to fix and is " 
thicker than air, and it is for this reason that the eye and 
its pupil are composed of water.^ This can be proved 
also from actual facts. When the eyes are destroyed 
water is seen to flow out of them, and even in their quite 
embryonic stage the eyes are exceedingly limpid and 
brilliant. Further, the white of the eye ^ in sanguineous 13 
animals is fat and oily, which serves the purpose of 
keeping the humid element from congealing. Conse- 
quently, the eye can resist cold better than any other 
organ of the body. No one ever experienced the sensa- 

the interior by reason of its fine, inbtlo nature, penetrates through these, 
as the light penetrates through the sides of the lantern and out through 
the atmosphere. In this way the images thrown off from things are 
iUuminated. Cf. Burnet, Early Ortek PhUowphyt p. 265. 

^ The aqueous and vitreous humours. 

'The sclerotica. 

154 Aristotle's psychology DinNsn 

tion of cold in the interior of the eye. The eyes of 
bloodless animals are covered with a hard skin 
which furnishes protection. The theory is altogether 

14 irrational which makes vision consist, as some hold, in a 
sort of radiation, and regards this radiation of something 
from the eye as extending to the stars, or as extending 
to some point and there effecting a combination with the 
object. It would be better to assume that this com- 
bination of the eye with its object were in the eye's 
original nature. But even this is nonsense. For what 
is one to understand by this combination of light with 
light ? Or how is such a thing to take place ? For 

438 d nothing combines in a haphazard way with anything else. 

15 Further, how can the internal light combine with an 
external one, for between them is the intervening 
membrane. Begarding the fact that there is no vision 
without light, we have spoken elsewhere.^ But whether 
the intervening medium between the visible object and 
the eye is light or air, it is in any case the motion 
through this medium that produces sight. And it is 
reasonable to regard the interior of the eye as composed 

16 of water ; for water is diaphanous. And as nothing 
external is seen without light, the same thing applies to 
the internal. The internal also must, therefore, be 
diaphanous. Since this diaphanous is not air, it must 
be water. For the soul or the perceptive power of the 
soul is not found on the eye's surface, but evidently 

17 within. Consequently, the eye's interior must be 
diaphanous and sensitive to light. And this we can see 
empirically. For cases have happened in war where 

1 De an. ilSb 1, 419a 9, 4a0a 16. 


persons have received sach a blow across the temples^ 
that the ocular conduits were severed and darkness 
seemed to ensue, just as when a lamp is put out, and 
this is due to the fact that the diaphanous, i.e. the 
pupil as we call it, was cut off, as in the snuffing of a i8 
lamp. If, therefore, this takes place in some such way as 
we describe, it is evidentlj necessary to render an expla- 
nation of this kind and to correlate each sense-organ 
with one of the elements, viz. the seeing power of the 
eye we must derive from water, the sense for sound from 
the air, and smell we must associate with fire. For the 
organ of smell is potentially^ what smell itself is 19 
actually. The sensible object stimulates the sensation 
into actuality, and consequently the latter must have an 
antecedent potential existence. Smell' is a smoke-like 
exhalation,^ and this is derived from fire. It is for this 20 
reason, too, that the organ of smell is especially assigned 
to the environment of the brain, for the material sub- 

^ The eye muBt be tranBlncent, and therefore oompoeed either of air 
or water, in order to tranamit vision to the inner soul, vision not taking 
plaoe on the eye's surface. This is proven by the fact that when the 
optic passages are severed, as Aristotle supposes, by a blow on the 
temple, one becomes blinded. 

•Cf. Dean, ina 12 ff. 

' De an. 421a 7 ff. 

^ Smell is considered by Aristotle one of the most difficult senses to 
analyze, which is due to the fact, he thinks, that it is very imperfectly 
developed in man. Taste is closely allied to it, but much better 
developed. The one is ooncemed with the ' sapid dry' (443a 7) and the 
other with the 'sapid moist.* Flavour is found in the moist only, 
while for respiring animals odour is found only in the dry. It can, 
however, exist in the moist as shown by the sense of smell in aquatic 
animals. For the latter reason it cannot be a ' smoke-like exhalation.' 
Aristotle appears here to be speaking only in terms of a current 
explanation. Cf . 443a 23 ff. 

156 Aristotle's psychology oisiNstr 

strate of cold is potentially wanxL And the same 
explanation holds good for the development of the eye. 
It is formed from a part of the brain, for the brain is the 
21 moistest and coolest member of the body. The organ of 
touch is derived from the element earth, and taste is a 
439 a form of toach. Consequently, the organs of these two 
senses, taste and touch, are found to conduct towards the 
heart The heart occupies a counterposition to the brain 
and is the warmest member of the body. Bearding the 
sense-organs of the body let the above determinations 


In the treatise On the Sovl^ I have given a general 
account of the objects of sense in their application to the 
several sense-organs, such as colour, sound, smell, flavour 
and the tangible I have explained their function and 
their activity, organ by organ. But we must also deter- 
mine what each of these things is apart from the organ, 
e.g. we must ask : What is colour ? What is sound ? 
What is smell ? What is flavour ? We must likewise 
inquire regarding the tactual, and we must b^in with 
colour. Everything has a twofold significance, viz. that i 
of actuality and potentiality. It has been explained in the 
treatise On the Sovl ^ in what way actual colour and actual 
sound coincide with and differ from the actual sensations 
of seeing and hearing. We must now explain what each 
of these sensible objects must be in order to produce 
sensation and its activity. We have already said in the 
above-named treatise regarding light that it is the colour 3 
of a diaphanous medium, accidentally produced.^ For 

^Dt an. 418a a&-424a 16. ^Dtan. 4QSb 29 ff. 

' Neither colour nor light belongs to the eesentud nature of the pel- 
lucid medium, which may be charged at one time with one colour and 
at another time with another, or in the case of darknem it may suffer 
privation of light. 


158 Aristotle's psychology dksbnsu 

when anything fire-like is found in the diaphanous, its 
presence constitutes light and its absence signifies dark- 

4 ness. What we understand by diaphanous is not a 
property peculiar to air or water or to any other 
so-called body, but it is a certain natural constitution 
and power, ^ common to both these bodies and found 
also in certain others, in greater or less degree, but 
which has no independent and separate existence. And 
furthermore, as there must be a limiting surface in 

5 bodies, so here also. Light is found in an indeterminate 
diaphanous. It is also evident that the diaphanous in 
bodies must have a surface, and that this surface is colour 
is plain from observed facts. For colour is found either 
in the boundary or it is itself the boundary. It is for 
this reason that the Pythagoreans^ characterized the 
visible superficies as colour. Colour, indeed, is given in 

6 the boundary properties of body, although it does not 
itself constitute that boundary. On the contrary, one 
must suppose that the same colour-quality^ which is 

439^ observed on the exterior applies also to the interior.^ 
Both air and water are seen to be coloured, for even their 

7 shimmer is colour. In these cases, however, air and 

^ Aristotle rejected the view of Empedoclee that light is motion and 
travels from heaven to earth (4186 20, 44Sa 26). Light is not motion, 
although it in caused by movement or change (dWoJoMrtt). In its own 
nature it is a definite qualitative condition of the air or water, just as 
the frozen represents a condition of water (4466 28— 447a 3). 

*Cf. Pint. BpU. Hem, L 15; Stobaei Eclog. L 15 quoted by Diels 
Dox. Or. p. 313. 

'The treatise On Coloura {vepl xp^A^^w) i> not genuine. Cf. Prantl, 
Aristot. aber die Farben, pp. 82-84. 

* Aristotle appears to have in mind such objects as jewels, whose 
colour he considers not merely superficial but as penetrating through the 


the sea, because of their unfixed character, do not have 
the same colour when viewed near at hand and from a 
distance. In solid bodies, on the other hand, the 
appearance of the colour is fixed, unless the surrounding 
medium makes it shift. It is evident, therefore, that the 
principle which is sensitive to colour is, in both the former 
and the latter instances, the same. The diaphanous,^ 
then, in so far as it is found in bodies (and it is found 8 
more or less in them all), causes them to be satu- 
rated with colour. Inasmuch as colour is found in the 
boundary of bodies, it would also be found in the 
boundary of the diaphanous substance. Consequently, 
colour might be defined as the boundary of the diaphanous 9 
in a definite body. Colour attaches also to diaphanous 
bodies themselves, such as water and other similar 
elements, and it is also found in all such bodies as have 
a surface-colour which is peculiar to the body^ itself. 
There is then, on the one hand, the possibility that the 
positive principle which in the air produces light should 
also be contained in the diaphanous ; on the other hand, 
it is possible that this should not be the case, but that 
the condition then should be one of privation. 

As in the case of air we have the two phenomena, 
light and darkness, so in bodies we have the two qualities, 10 

^The diaphanous is that which mediates colour, and light is that 
which converts the potentiaUy diaphanous into the actually diaphanous. 
In other words, a diaphanous or pellucid medium, such as air or water, 
is not actuaUy peUucid without light, but is dark. Colour has the 
power to set the diaphanous in motion (419a 10), by which means the 
images of remote surfaces affect the vinial organ. 

^ Fire or some positive principle such as is found in the aether is sup- 
posed to illumine the diaphanous ; the withdrawal of this is darkness 
or the privation of light. 



white and black. Regarding the other colours we must 
now decide, after analysis, in how many ways they can 
be produced. For black and white may be so juxtaposed 
that each of the two, on account of its minuteness, when 
takeu alone will be invisible, while the combination of 
the two will be visible. The latter cannot be seen 

11 either as white or black. But inasmuch as it must have 
some colour, and it can be neither of these two, it must 
be a mixed colour, and different in kind from the others. 
It is, then, a possible supposition that there are several 

12 colours besides white and black, but their maoifoldnesa is 
due to proportion.' This proportion can be expi-essed by 
the relation of 3 : 2 or of 3 : 4, or colours can be related 
to each other in terms of other numbers, and some may 
not be expressible at ail in terms of any proportion, but 
in terms of some iucommensurable plus and minus. The 
same thing applies also to harmony of tones. Those 
colours which are expressed by harmonious numbers, as is 
also true of tone- harmonies, appear to be the most pleasing, 

440 a such as sea-purple, crimson, and a few others like them ; 
they are few for the same reason that harmonious tones 
are few.* The other colours are not numerically expres- 
sible. Or, is it true that all colours are numerically 

' Whit« and black, the correUtea of light and darkness, are the 
baaal colours, as sweet and bitter are the basal fiavoura. Between tbeie 
two extreme oppoaites there are interiDGdiate colonrs, into which the 
primary colon n are convertible b; composition {Phya. lSSa32 t ISBt 21 ; 
2-29A U; Mttaph. lOdTa 33). These intermediate colours are red, 
violet, green, blue, and yellow. Gray is included in hUok, and {■ Dot 
re^rdcd u an independent colour, while yellow ia perhaps included in 
white (442a 22). Cf. Goethe. Farbmlehre (ed. ISIO), Bd. 11. pp. 11-53. 

' In the first place because they do not form a contjuaum, and so are 
not iniluitely or indefinitely divisible, and secondly beoaiue Uwy are 
objects of feeling. 


expressible, although some colours depend upon a r^;ular 
order, while others depend upon an irregular order, and 
the latter have this character when they are not pure? 
This is one^ explanation of the genesis of colours ; another' 
explanation is that they shine through one another, as we 13 
see sometimes in the works of artists, when they superadd 
a colour on a background of a dififerent colour, e,g. when 
they wish to produce the effect of an object seen in the 
water or in the air. So it is also with the sun, which in 
its own nature appears white, but red when seen through 
mist and smoke. And many other colours will be pro- 14 
duced in the same way as above described. That is to 
say, a certain proportion might be supposed to exist 
between the colours on the superficies and the colours in 
the depths, and others again may not be expressible in 
terms of ' proportion ' at alL It is, therefore, absurd to 15 
say with the ancients that colours are efiSuxes, and for 
this reason are visible. For in their opinion it is 
absolutely necessary that sensation be effected through 
contact, and it is consequently better to say at once that 
the medium of sensation is set in motion by the sensible 
object, and that in this way sensation is produced by 
contact and not by efiSuxes. In the case of juxtaposed 16 
colours, just as one must suppose an invisible magnitude, 
so must one suppose an imperceptible moment of time, 
in order to explain the fact that the movements issue 
imperceptibly, and because they are simultaneously visible 
the impression is a single one. There is, however, no 
such necessity here, but the colour on the superficies 

^ Viz. the namber-theory which Ariatotle rejects. 
' AJflo this theory of superposition is rejected. 



when unmoved, and when set in motion hy its substrate, 
produces unlike motions in the medium. Consequently, 
it appears different, and neither white nor black. So 

17 that if an invisible magnitude is uot possible, but every , 
magnitude must be viaible from a certain distance, bo 
there must be here also a certain mixture of colours. In 
this way one may suppose that in objects viewed from a 
distance a certain common colour is seen. For that there 

18 is no invisible magnitude is a matter that must be is- 1 
44oi vestigated later. If a mixture' of bodies takes place, then 

it is not merely in the way that some think, viz. by the 
juxtaposition of minimal parts which are imperceptible to 
our senses, but also in the form of a general mixture of 
the entire substance together, as explained in outline in 

19 our treatise On Mieture.^ By the former method of com- 
position only those substances can be mixed which are 
capable of analysis into minimal parts, eg. men, horses, or 
seeds. In the case of 'men,' a man is the minimal 
part;^ in the case of 'hoisea,' a horse. Consequently, in 
both instances the mass is formed by juxtaposition of 
these minimal parts. We do not, however, speak of a 

20 man being mixed with a horse. Whatever cannot be 
analysed into minimal ([homogeneous]) parts, is incapable 
of mixture in this sense, but only in the sense of total 

'The first two tbeoriea, v'lr.. the oumerical and the auperpwiUonai. 
sre here rejected in favour of the theory of substuitiiJ mixture. 

'This treatite (vtpl ^ifeui) haa besD lost. For Aristotle 'b deSaltion 
of miitare, and his distinction between it and synthesis, see De gen. it 
corr. 328a G ff. The former implies homogeneity, while the Utter 
may be merely mechsiucal juxtapusltion. The former produces a whole, 
the latter ui aggregate (321a U). 

'Read ^dx"rror for iXixicw. Cf. Btrlincr Wochtiachri/i filr eitut. 
Phiiol., 1898, p. B88. 


mixture, which is what naturally takes place in most 
cases. In our treatise On Miature we have already 
explained how this can take place. Where bodies are 21 
mixed their colours must evidently be mixed also, 
and this is the principal cause of the multiplicity of 
colours, which is not explained by their being super- 
posed or by their juxtaposition. It is not true that 
what is mixed has one colour when viewed near by, and 
another when viewed at a distance, for it has one colour 
when viewed from all points. And colours will be 
manifold because of the possibility of manifold proportions 22 
being employed in mixtures, some of which will be based 
on numerical proportion, others on that of disproportionate 
mass. Further, the same thing may be said of mixed 
colours as was said of juxtaposed and superposed colours. 
The explanation of the fact that we have fixed and 
definite varieties of colours, flavours, and sounds will be 
given later.^ 

1 Gf . De senau, 4456 3 ff. ; 446a 20. 


We have now explained the meaning of colour and the 
cause of its multiplicity. We had already discussed 
the subject of sound and articulate speech in the treatise 
On the Send} Smell and flavour now remain to be 
discussed. Both these terms signify almost identical 
natural affections, only each of them is found in a 

2 different organ. The quality of flavours is more distinct 
to us than that of smells. The reason is that our sense 

441 a of smell is inferior to the same sense in other animals, 
and is inferior to all our other senses, while we of all 
animals have the most accurate sense of touch, and taste 

3 is a sort of touch.* 

Water in its own nature has no flavour. And yet 
it is necessary that water should contain within itself 
the varieties of flavours, which owing to their infini- 
tesimal character are indiscernible, as Empedocles^ says, 
or else there must be in water some such matter as is 

1 De an, 4206 32. SjDe an. 423a 19. 

^ Other than this we have no knowledge of the Empedoclean theory 
of taste, with the exception of the statement in fr. 139 that flavours 
depend npon adaptability to the sense-pores. Of. Burnet, Eariy Oreek 
PhilM, p. 266. 



the universal germ-origin of flavours,^ and in this way 
all flavours are generated out of water, different flavours 
from different parts; or again, supposing that water 
contains no qualitative differences, we must then find 
some other efficient cause of flavour, such as heat or 
the influence of the sun. The error of the Empedoclean 4 
theory is very easy to detect. For we actually observe 
flavours undergoing change under the influence of heat, 
e^. when we expose fruits to the sun by removing 
their pericarps or by heating them before a fire. They 
do not acquire this new flavour by drawing it out of 
the water, but by undergoing a change in the removal 
of the pericarp itself When fruits are dried and stored 
they become in time, instead of sweet, pungent or bitter, 
or change their flavour variously, and when cooked they 
acquire, so to speak, all sorts of flavours. So too, the 
theory that water is a panspermic matter is impossible. 5 
For we observe that out of one and the same thing, 
as out of the same food stuff, different flavours are 
generated. There remains the theory that water by 
undergoing some external influence, chtmges. It is plain 6 
that the phenomenon which we call flavour is not due 
to the potency of heat. For water is the thinnest of 
all liquids, subtler than oil itself Oil, however, is more 
expansile than water because of its viscous character, 

' I think the reference here is more likely to Anaxagoras than to 
Democritns, as Wallace supposes (Aristotle's Pvychdogyt Introd. p. Ixvi), 
although both of them are said to have used the term inuf^wtpiiia. The 
description of the theory (441a 19) as one of dynamism would conform 
better with the general principles of Anaxagoras than with the 
mechanical philosophy of Democritns. In strictness, iroMowtpfda i^ a 
term which Democritns could not legitimately use. 

166 Aristotle's pstcholooy dssbkbu 

water being non-cohesive. For this reason it is harder 
to hold water in one's hand than it is to hold oiL 

7 Now, since water is the only liquid which when heated 
exhibits no denser consistency than before, we most 
evidently look elsewhere for the cause of flavour. For 
all flavours are more dense when heated. Heat is a 
contributing cause ([not the sole one]). Apparently the 

441 b flavours that are found in fniits have a prior existence 

8 in the earth. In the same spirit many of the ancient 
physiologers ^ say that water is like the soil through 
which it passes, and this is particularly evident in the 
case of salt waters, for salts are a form of soil Also, 
water that has been filtered through bitter ashes acquires 

9 a bitter taste. Further, we often find springs that are 
bitter and others that are pungent, while others still 
have different flavours. The greatest variety of flavours 
is found, as one might suppose, amongst plants. It is 
the nature of moisture, as of other things, to be affected 
by its opposite and its opposite is the dry. Conse- 
quently, it is affected by fire, which is by nature dry. 

10 Now, heat is the peculiar property of fire, and the dry 
is the peculiar property of the e€u:th, as was said in 
the treatise On the Elements? Neither fire, nor earth, 
nor any other element, as such, acts or is acted upon. 
It is only in so far as each thing contains in itself the 
principle of opposition that it either acts or is acted upon.' 

^ Lewes finds this idea expressed in Hippocrates. Of. Aristotle, p. 260. 

'The reference is probably to De gen. et corr. 3296 18-3306 9. On 
the lost treatise rep2 vroLxti^p see Heitz, Die verlorenen 8chr\ften d. 
Aristoteles, p. 76. 

'A thing acts or is acted npon throogh certain of the qualities 
possessed by it and through the action of opposing qualities. 


As, therefore, those who dissolve a colour or an 
flavour in water, cause the water to absorb it, so 
nature acts upon the dry and earthy elements, and 
by filtering water through these elements and stimu- 
lating them into activity by heat, it causes the moist 
element to acquire a certain quality. This condition, is 
which is wrought in moisture by means of the above 
mentioned dry element, is flavour, and it consists in 
the conversion of a potential (taste into an actual one.^ 
For the sense-organ which is already in a condition of 
potentiality, passes over into a condition of actuality. 
The process of sensation does not resemble learning so 
much as it resembles contemplation. That flavours do 
not attach to everything dry, but only to the dry that 13 
is nutritive, either as a positive or negative condition, 
one may conclude from the fact that th6 dry is not 
found apart from the moist nor the moist apart from 
the dry. Neither one when taken alone is food-stuff 
for living creatures, but only when combined. In 
animal food it is the tactual elements which effect 14 
growth and decay. And it is by virtue of the warmth 
or cold in the assimilated food that these phenomena 
are produced. For these are the properties that cause 
growth and decay. The administered food nourishes in 442 a 
so far as it is gustable. For everything is nourished 
by means of the sweet, whether pure or mixed. This 15 
subject must be more definitely treated in the work 

' The gustable or flavonr (xvM^t) u described at 4416 19 as an effect 
prodnoed in a moist substance by that which is dry. Flavour is 
therefore, the sapid moist, whOe the object of smeU is described (443a 2) 
as the * sapid dry.' The odoriferous and the gustable (sayour and 
flavour) are dosely allied. 


On Generation ' ; for the present we only touch upon 
it so far oa necessary. Heat disposes to growth and 
brings food into a prepared conditioa ; it absorbs what 
is light and rejects the salt and bitter because of 
their heaviness. What external heat effects in external 
bodies, is also produced by internal heat in animals 
i6 and plants. Nourishment, then, is caused by the sweet. 
The other flavours are mingled in food in the same 
way as the bitter and pungent, i.e. to serve as a 
relish. This is for the purpose of counterbalance, and 
because the sweet is over-nutridve and swims on the 

As colours are a combination of white and black, eo 
flavours are derived from sweet and bitter. They depend 

17 severally on a proportion of more or less, on a proportion 
of mixture and motion either numerically expressible, or 
indeterminate. Those mixtures, however, which produce 
pleasure are numerically expressible. The oily flavour ifl 
to be classed with the sweet; the salt and bitter are 
closely allied, while the sour, pungent, astringent, and 

18 acid are intermediary. And so the varieties of flavours 
and colours are pretty nearly the same in number; for 
there are six of each, if one regards, as is reasonable, the 
gray as a sort of black.* We have then to include 
yellow in white, just as we referred the oily flavour to the 

e referring to the subject of growth uid deosy, not 
a treated iii De gtn. ti rorr. 3S))a 



of taate. The snbjeot u 

^ And further, if one regards yellow as a Bpeoies of while. Otherwiu 
we have leveo coloara aa eaunierated at note '2, p, 8?. I have retained 
Susemihl'a conjecture f{ for irri, adopted by Biehl (cf. Alexander 
Aphrod. CotninerU. ad loc.). Prantl, however, calls the Aporia of 
AlH:iaiider " ungeechiokt " {ArifM. Utber die Farhtn, f. 117). 


sweet, while crimson, sea-purple, green, and blue, are 
intermediary between white and black, and all other 
shades are combinations of these. As black is privation 19 
of the white in a diaphanous medium, so the salt and 
bitter are privation of the sweet in a nutritive moist 
substance. Consequently the ashes of anything that has 
been burnt are bitter ; for the potable element has been 

Democritus and most of the physiologers who treat the 
subject of sensation make the most remarkable blunder, 
for they resolve all sensible objects into the tangible. If, 442^ 
indeed, this is correct, each of the senses becomes evidently 20 
a sense of touch. It is not difficult to see that this is 
impossible. Further, they treat the common fimctions of 
all the senses as special functions. For the perception of 
magnitude, figure, roughness, smoothness, and sharpness 
and bluntness in solid bodies, is the common function of 
all the senses, and if not of all, then at least the common 
function of sight and touch. It is in these perceptions, 21 
therefore, that the senses are subject to error ; but they 
are not subject to error in their special sensations, 
e.g. sight is not fallible regarding colour nor hearing 
regarding sound. Again, these physiologers refer the 
special functions to the general, as Democritus does with 
white and black,^ the latter of which he identifies with 
the rough and the former with the smooth, and he 

^ White is due to smooth atoms mnd their aggregation is a smooth 
surface. Black is due to rough and uneyen atoms and their aggrega- 
tion is a rough and uneven surface (cf. Theophrastus, Dt mimic, 73). 
Further, however, the quality of the vinble is affected by the rapidity of 
motion in the effluxes and by the condition of the air itself (Theoph. 
Dtaeneu, 80). 

170 Aristotle's psychology Dnmmo 

reduces flavours^ to atomic forms. And yet it is 
either not the function of any sense to discern common 
properties, or else this power belongs to the eye more 

22 than to any other organ. K, however, this power 
fjEdls rather to the lot of taste, it is at any rate the 
function of the most delicate sense to discriminate the 
slightest distinctions, each after its kind, so that taste 
would have to discriminate common properties better than 
any other sense and be the most discerning judge of 

23 atomic figures. Further, all sensible objects contain the 
principle of opposition, e,g. in colour black is the opposite 
of white, and in flavour bitter is the opposite of sweet; but 
one figure does not appear to be the opposite of another 
figure, for to what sort of polygon would a circle be 

24 opposed ? Further, the atomic figures being infinite in 
number, it necessarily follows that flavours are also 
infinite in number. For what is the explanation of the 
fact that one flavour produces a sensation and another 
flavour does not produce it ? 

We have now treated the subject of the gustable and 
flavour. The other aspects of flavour receive their 
proper consideration in the treatise On the Physiology of 

^ FlAvour-qualities are explained by Democritm in a way similar to 
variationa in oolonr, t.e. white and black are analogons to sweet and 
bitter. Sweet is dne to round smooth atoms ; bitter to rough and 
angular ones (Theoph. Dt aeiMU, 65, 66). 

' The two books on plants (r€/>2 ^txrrQp) are frequently referred to by 
Aristotle (468a 31, 4676 4, 656a 3, 7836 20) and «re mentioned in the 
catalogue of Diogenes Laertius, but were apparently lost as early as the 
time of Alexander Aphrodisiensis {flor, drca 220 A.D.); of. Zeller, 
ArisMle, Eng. tr. Vol. L p. 91. 


Ik like manner one must also treat of smelL For the 
same effect which is produced by the dry or the moist, is 
produced in another connection by savoury moisture in 
air and water equally. Now we observe that the 
diaphanous is a common principle in these two elements ; 
the element, however, is not odoriferous by virtue of its 
being diaphanous, but by virtue of its capacity to exude 443 a 
and throw off dry savour. For smell is exercised not 
only in the air but also in water. This is evidently so 
in the case of fishes and mollusks^; for these are known 2 
to be endowed with smell although there is no air 

^The Testaoea {darpoLKMep/M), as used by Aristotle, inolnde the 
MolliMca (in the modem meaning), excepting the Cephalopoda. They 
include also the Ascidians and Echini, although these are sometimes 
grouped by Aristotle amongst the Zoophytes. The Testacea form the 
lowest group in the animal scale, lacking as they do the power of 
locomotion and the higher senses, as sight and hearing. The MoUusca 
(/MftXdirca) correspond to the modem Cephalopods, and the Crustacea 
{/iaXMcdffTpoKa) include the crabs, crayfish, lobster, etc., which have a 
soft interior and a shell-like exterior, the shell being, however, flexible 
and not brittle as in the case of the Testacea. These three classes 
and the Insects (Irro/ia) form Aristotle's four classes of bloodless 
animals. Cf. Ogle's AriatoUe on the Paris of AninuUs, pp. xxix, 222; 
Meyer's AriatoUUs 7%ierhmde, pp. 169 ff. 


172 Aristotle's psychology dsbbnsu 

in the water (for the air comes to the surface when 
found in water) and they have no respiration. If one 
assumes that both air and water are moist elements, 
smell would be the dry sapidity in the moist and such 

3 would be the nature of an odoriferous body. That this 
condition in an object is derived from a sapid element is 
a plain conclusion from things that do and do not emit 
smelL For the simple elements, such as fire, air, eartii, 
and water, are non-odorous because the moist and dry in 
them are non-sapid, excepting when a combination is 

4 produced. This is why even the sea has a smell ; it 
contains a sapid dry element Salts are more odorous 
than nitre, as is proven by the oil derived &om them. 
Nitre, in turn, is more odorous than earth. Further, a 
stone is inodorous, for it is without sapidity ; woods, on 
the other hand, are odorous, for they are sapid, and 
amongst woods those that are watery are less odorous. 

5 Further, amongst metals gold is inodorous, for it is not 
sapid; bronze, however, and iron are odorous. When 
the moist element is burned out of metals, the slag 
becomes still less odorous. Silver and tin are more 
odorous than some and less odorous than other metals ; 

6 for they contain moisture. Some writers r^ard smell as 
a smoke-like exhalation which is common to earth and 
air [and all the naturalists fall back on this explanation 
of smell]. And so Heraclitus made the remark that if 

7 all things were smoke, we should discern everything by 
our nostrils. Now, the naturalists all explain smell on 
this theory, some of them describing it as vapour, others 
as an exhalation, and others as a combination of both of 
these. Vapour is a kind of moisture, whereas a smoke- 


like exhalation is, as we have said, common to air and 
ectrtb. Water is derived from vapour, and a sort of 
earth is developed from smoke-like exhalation. But 
neither of these two seems to be the odorous. For vapour 8 
is due to water, while smoke-like exhalation canfiot possibly 
be generated in water. And yet creatures that live in 
the water have the sense of smell, as was said above. 
Again, exhalations here have the same meaning as emana- 443 ^ 
tions, and if the emanation theory was wrong, so is this 
wrong. It is clear that the moisture which is found in 9 
the air (for the air also has a moist character) and in water 
is capable of deriving something from the sapid dry element 
and of being affected by it. Furthermore, if the dry 
element, when saturated, as it were, acts in moisture in 
the same way as it does in air, smells must evidently 
correspond to tastes. But precisely this fact is found in 10 
certain flavours and savours. For there are pungent, 
sweet, harsh, astringent, oily smells, and one might say 
that rancid odours correspond to bitter tastes. As the 
former, therefore, are revolting to the taste, so rancid 
tastes are revolting to the smell. Evidently, then, that 
quality which in water is flavour, in air and water is 
smell. This explains why cold and frost blunt flavours n 
and obscure smells. For cold and frost nullify heat, 
which is the moving and active principle here. 

There are two sorts ^ of odorous objects; for it is 
untrue that there are no varieties of odorous objects, as 
some maintain. Such varieties do exist. One must, 
however, explain in what sense this is true and in what 12 
sense not true. One variety corresponds, as clearly 

^ The agreeable and disagreeable. 

174 Aristotle's psychology Digsmu 

explained, to flavour, and contains the pleasurable and 
painful accidentally. For owing to the fact that these 
smells concern our nutritive power, thej are agreeable to 
those who have desire and disagreeable to those who are 
sated and feel no desire. Neither is the smell agreeable to 
those to whom the food which has the smell is disagreeable. 

13 Consequently, these smells contain, as we said, the pleasant 
and painful accidentally, and this is the reason why they 
are common to all animals. There is another variety of 
smells which are pleasant in themselves, e.g. the fragrance 
of flowers. For they incite us in no respect, whether more 
or less, to food, nor do they in any way contribute to the 
stirring of any desire; they have rather the opposite 
effect What Strattis ^ says, mocking Euripides, is true : 

When lentil-soup you cook, 
Pray, add no spices to it 

444 A By mixing such spices in their potations, men now-a-days 

14 force pleasure, as is their habit, believing that the 
pleasure which is really derived from two sensations* is 

15 derived from only one. Smell of this sort is peculiar to 
man, but smell that is based on flavour is sensed by 
other animals,' as remarked above. The varieties of the 

^ Strmttis, of Athens, the oomedisn {for, 410 B.O.). Ct Meineoke, 
Fragm, Com, Ortue. p. 4S6. 

'The pleasures of eating and drinking are oombined from smell and 

' The qnalities of smell are few and inexaob, becanse of the lack of 
deyelopment of this sense in man {De an, 421a 10). Man possesses 
the most deUcate sense of toaoh and the worst sense of smelL In the 
lower animals smell is merely a handmaid of toaoh, while in man it 
not only serves in this capacity but interprets the odoriferoos world as 
plessant and onplessant per «e, t.e. apart from its assodatioB with 


latter, because the pleasant is incidental, are classified in 
t^rms of flavours, which does not apply to the former 
class, because there the smell is pleasant or disagreeable in 
itself. The reason why this class of smells is peculiar 
to man is because of the condition of his brain. For i6 
man's brain is by nature cool, and the blood in its 
surrounding veins is thin and pure, though easily chilled 
(which explains why the evaporation of food when cooled 
in this region causes catarrhal colds), and so this variety 
of smell has been developed in man as beneficial to his 
health.^ For no other function can be ascribed to this 
class of smells, although this function is evidently 17 
exercised by them. Food, whether solid or liquid, 
although agreeable, is often harmful; but the smell 
exhaled from savoury food indicates, one may say, what is 
absolutely and always beneficial to man in whatsoever 18 
condition he is. Consequently, smell is mediated by 
respiration, not in all animals, but in man, the quad- 
rupeds and such other sanguineous animals as have a 
larger share in the employment of air. For smells being 
transmitted to the brain by virtue of the levity of the 
heat in them, the regions about the brain are thereby 
the more healthy. For the potency of smell is naturally 
wann. ^Nature employs respiration for two purposes; 19 
its main purpose is to assist the functioning of the 
chest ; its secondary function is to transmit smell. For 
in respiration the air produces, as it were in passage, 
motion in the nostrils.^* Smell of this sort is peculiar to 20 

1 Owing to their warm, dry nature. 

'Thisaentenoe ia ont of oonnection with the foUowing one, and the 
paaaage enoloaed in aateriaka should probably be inserted at tht markf 
4446 7. 

176 Aristotle's pstcholoot Dvanrou 

human nature, for man has, in proportion to his size, 
the largest and moistest brain of all animals. For this 
reason man is the only animal, one may say, that senses 
the smell of flowers and similar smells, and finds pleasure 
in them. For the warmth and movement in these 
444^ smells is proportional to the excess of moisture and 
coolness in the brain. To the other animals that are 

21 endowed with lungs for respiration, nature has given the 
perception of another kind of smell, so as to avoid the 
creation of two sense-organs. It is enough for these 
respiring animals that they have the sensation of only 
one class of smells, while man discriminates both 

22 classes. tThat the non-respiring animals possess the 
sense of smell is evident. For fishes and all the varieties 
of insects, on account of the connection between food and 
smell, distinguish smells with precision and at a distance, 
as we observe in the case of bees and that variety of 
small ants sometimes called cnips ^ and purple sea-fish, 
as well as in the case of many other similar animals which 
have a keen sense of smell for food. The organ of sensation 

23 is not so clearly defined. One might, therefore, raise the 
question as to the organ of the sense of smell, although 
smell is mediated exclusively by respiration (this is 
plsdnly so in all respiring animals). None of the above- 
mentioned animals, however, respire, and yet they 
perceive smells, unless we are to assume an additional 

^ The term ' Cnips ' has come into nte in Zoology to describe a beetle 
aUied to the Cryptarcha (of. E. Reitter, Ft '*. Ver,, BrOnn, xii. 1873, 
p. 163). The reference here, however, appears to be to some small 
variety of ant such as the formica flava, or to the common red ant 
(monomortttm pharaonis^ cf. Comstock, ManwUfor tht Study of ln»teU^ 
p. 043). 


sense beyond the five, and this is impossible. For it is 24 
smell that senses the odorous, and these animals detect 
odour, though perhaps not in the same way as respiring 
ani m als. In respiring animals the breath lifts up a 
superficial membrane, a sort of cover, as it were (for 
which reason they do not smell without respiration), 
whereas in the non-respiring animals^ this is lacking, just 
as over the eyes some animals have eyelids and without 
lifting these do not see, while others are hard-eyed and 
have no lids, and so do not need to lift any covering, but 
see at once from the moment they are able to see. And 25 
so, too, no other animal feels discomfort from a smell 
which is intrinsically malodorous, unless it chances to 
be harmful But by these harmful smells animals are 
sometimes destroyed, just as men often get a headache 
from coal-gas and frequently lose their lives. In the 
same way other animals are destroyed by sulphur and 
asphalt fumes, and because they are so affected by such 445 
fumes they avoid them. But for malodour, as such, they 26 
take no thought (although many vegetables have bad 
smells), excepting in so far as taste or food is influenced 27 
by it. 

Inasmuch as the number of the senses is uneven, and 
every uneven number has a middle term, it seems that 
smell occupies a middle position between the senses that 

^ In aqnatic animalw gUU perform a fonotion analogoua to the InngB 
in respiring animals. A similar fonotion is performed in inseots by the 
membrane at the junction of abdomen and trunk (De reap. 4785 16, 
475a 8). The gills in fishes and the membrane in insects do not, how- 
ever, appear to mediate smell, as the lungs do in respiring animals. 
Owing to the semi- tangible nature of odour, it appears to act directly in 
these cases, t.e. by impinging immediately on the sense-organ without 
the assistance of inhalation. 


178 Aristotle's psychology desbssu 

operate bj direct contact, viz. touch and taste on the one 

28 hand, and those which function indirectly through a 
medium, viz. sight and hearing on the other hand. 
Consequentlj, the odorous object is something which 
affects foods (for these fall under the category of the 
tangible), and, further, it affects audition, because smells 
are sensed in the media of air and water. Smell, 
then, is in a way common to these two things, and is 
found in the tangible, the audible, and the diaphanous. 
It is with good reason, therefore, that smell has been 
compared to the imbruing and washing of a dry element 

29 found in the moist and liquid. Begarding the sense in 
which one may or may not apply the term ' species ' to 
odours, let the foregoing discussion suffice. 

There is a view held by certain Pythagoreans, which is 
ill-founded. They hold that certain animals feed on 

30 smells. Now we observe, in the first place, that food is 
a composite thing, for the creatures which are nourished 
are not simple, and consequently there is an excrement of 
food, sometimes within the animal itself, and sometimes 
external, as in the case of plants. Further, water when 
taken alone and unmixed is not fitted to yield nourish- 
ment, for what is assimilated into the body must be of a 
solid nature. Again, it is much less reasonable that air 

31 can become solid matter. In addition to this, we observe 
that all animals have a receptacle for food, from which 
after its entrance the body assimilates it. The sense- 
organ, however, is situated in the head, and smell enters 
with a breath-like inhalation, so that it penetrates to the 

32 respiratory region. That smell, as such, does not contri- 
bute to nourishment, is plain. That it does, however, 


contribute to health, is evident from the sensation itself 
and from what has been said,^ so that what flavour is to 
the nutritive organ and to the parts nourished, this smell 
is to health. Let these, then, be our conclusions regard- 445^ 
ing the several sense-organs. 

^Namely from its association with food and from the effect of 
inhaled warmth on the head. 


One might raise the question whether, supposing all 
bodies to be infinitely -divisible, the sensible qualities of 
bodies are also infinitely divisible, such qualities as colour, 
flavour, smell, sound, weight, cold, heat, lightness, rough- 
ness, and softness. Or must we say that this is impos- 
sible ? For every one of these qualities produces 
sensation. They all receive their name from their 

2 capacity to stimulate sensation. Therefore sensation 
must be infinitely divisible, and every magnitude must be 
sensible. For it is impossible to perceive a white object 
without its having dimensions. Were this not true, it 
would be possible to have a body without colour or 
weight or any similar quality, in which case it would be 

3 absolutely imperceptible, for these qualities constitute 
the sensible. The sensible then would have to be com- 
posed of the non-sensible. But it must be composed of 
sensible qualities, for it cannot be composed of mathe- 
matical elements. And, furthermore, what organ could 
we use for the discrimination and cognition of such 
elements ? Could we employ reason ? But they are not 
rational elements, neither does reason think the external 






world, excepting in conjunction with eenaation.^ At the 
'vame time, if this view of the infinite divisibility of aensible 
qualities were true, it would appear to furnish support for 
the advocates of atomic magnitudes. For in this way the 4 
problem would be solved. It is, however, imposflible. 
■Thie subject has been discussed in our treatise On Motvm? 
In the solution of these questions one will see why it ia 
that the various forms of colour, flavour, sound, and other 
sensible qualities, are determinate, For in things that 
have extremes, the internal properties must also be 
{'determinate. The opposite is an extreme. Now, every 5 
'sensible quality implies opposition, £.g. in colours, white and 
-black ; in flavour, sweet and bitter. And in everything 
else the opposites form extremes. The continuous is there- 
fore divisible^ into infinite unequal parts, but into deter- 
minate equal parts. Now, whatever is not in its own nature 
continuous is divisible into determinate forms. Inasmuch 6 
as qualities must be interpreted as forms, and inasmuch 
as continuity is always given in these, we must suppose 
a difference between the potential and actual This is 
why the ten thousandth part of a visible grain of millet 
is unseen, although the eye rests upon it, and so too a 446 a 
quarter tone is undetected by hearing, although the whole 

.nly i. 

a of imagGB, which 

Reason ihinka the exMrnal world 
we derived from aeuuitioii (Dc 1 

The reference is to the iaflt threa books of the Phykx, which are often 
referreii to by Ariatotle m wtfi (ifiitrtuir (c(. 272a 30, 299o 10, 318a 3, 
1049b 36). The particular reference here is to the diwuaiioD of 
' continnitf ' and ■ divisibility' in Physifa, 213a 21 S. 

>A1I magoitudea are inflnitely divtmble (PAya. 206a 10 ff.}, and all 
nnmber ia capable of being infinitely increased. Althongh magnitudea 
are infinitely divisible, their iadnity is only potential. The iiiQiiit«ly 
•mall particle baa only a notii 



7 continuoiis melody is heard. But the interval from 
mean to extreme is not appreciable to us. And the same 
thing applies to the excessively small amongst other 
sensible objects. They are discernible poteutiiilly, but not 
actually, and when regaTded in isolation. A foot-line is 
contained in a two-foot line potentially, but actually only 
s after division has been made. When excessively small 
parts like these are separated off, it is reasonable to 
suppose that they would be lost in their environment, 
9 just as a tiny particle of flavour is tost in the sea. 
Nevertheless, since this excessively small particle, nhen 
regarded in itself and in isolation, is imperceptible (for the 
excessively small has only a potential existence in a body 
that is more discernible), neither is any sensible object of 
this sort, in isolation, actually perceptible, and yet it is a 
sensible object, because it is so potentially, and wilt be 
actually so, when added on to aomething. We have now 

to explained that certain magnitudes and qualities are imper- 
ceptible, and have stated the reason for this, and have 
shown in what sense things are perceptible, and in what 
sense they are not. When, however, inherent qualities 
are so constituted in reference to themselves as to be 
actually perceptible, and not merely so in conjunction 
with an entire body, but also when regarded alone, then 

It colours, flavours, and sounds, must be numerically limited. 
One might raise the question whether sensible objects 
or the movements excited by sensible objects — whatever 
be the way in which sensation is effected by their 
activity — are flrst transmitted to a medium, as appears to 
be the case with smell and sound. For a petson 
standing near by has an earlier perception of a smell. 


and a sound reaches one sometime after a blow. Is the 12 
same thing true of the visible and of light ? According 
to Empedocles sunlight is first transmitted to a medium 
before it reaches the eye or the earth, and this seems to 13 
be reasonable. For whatever is moved is moved from 
one point to another, so that a certain time must elapse 
in which motion from one point to another takes place. 
But all time is divisible, and consequently there is a 
moment when the ray is not yet visible, but is still in 446^ 
transit in the medium. Also if everything at the same 14 
moment hears and has heard, and in a word perceives 
and has perceived and there il no time process in 
sensations, nevertheless they lack this process in the 
same way^ in which sound, after the blow has been 
struck, has not yet reached the ear.^ The shifting of 15 
letters also shows this plainly, because their movement 
takes place in a medium. For people appear not to 
have heard what was said because the air' has shifted. Is 
this true also of colour and light ? For it is not owing 16 
to a particular condition that one thing sees and another 
is seen, like two equivalent terms. For it would not 
then have been necessary for either to be in a given 
position. For when things are equivalent, nearness or 
remoteness from each other makes no difference. It is 17 
reasonable that succession in time should be found in 
sound and smell, for like air and water, they are 

^ Bead bfioUn for 6fuaf, 

*The paasage of time has taken place in the medinm, although one 
may not be conscioos of it. Aristotle defines time as the measure or 
nomber of motion {Physica, 2l9a 10 ff ; De eoelo, 279a 14). 

* The letters have become shifted in the air or medium, so that one 
hears a word wrongly. 



continuous, and yet their movement is divisible, and so it 
sometimes happens that the nearest and most remote 
persons perceive the same smell, and at other times this 
is not the case. 
i8 Some persons 6nd a difficulty also in the following. 
It is impossible, some say, for different persons to hear, 
see, or smell the same thing in the same way. For it ie 
impossible for several persons who are separate ftom 
each other to hear and smell alike ; in that event the 

19 unitary object of sensation would have to be separated 
from itself. The primary stimulus, as a bell, frankincenae, 
or a fire, is perceived by all as numerically one and the 
same, but in its peculiar qualities it is perceived with 
numerical differences, though in its essential nature as 
one and the same thing ; for wldch reason many persons 
see, smell, or bear the same thing at the same time. 
One is not concerned here, however, with bodies, but 
with qualities and motion (otherwise we should not have 
this phenomenon), which are impossible apart from body. 

20 The question of light is different ; for light has a sub- 
stantial nature and is not a motion ' ; in genera! the 
same determinations are not to be applied to trans- 
formation and motion. Spatial motions take place, as 
one might suppose, first into a medium (sound is thought 
to be the motion of something subject to spatial change), 

47 a whereas that which undergoes transformation does so in 
a way different from spatial change. It is possible that 
transformation takes place in mass and not first by 

■ EnpedocleB bid described light u motion (cf. Dc an. ilSb 20). 
Ariitotle od the other band regards it as a qualitative change in the 
diaphuiaiu. It, therefore, represent* k coodition in a pbyeical body 
(ftir or WKter), ctd. note 1, p. 159. MEDIUM OF SENSATION 185 

halves, as in the case of water which freezes at once 21 
entire. Nevertheless, if what is being heated or frozen 
should be of considerable bulk, one part is affected by the 
adjacent part, and the first part undergoes changes 
through its own alteration, and it is not necessary that 
the entire mass undergo alteration at the same time. 
Taste would also be subject to the same conditions as 22 
smell, if we lived in a medium of water and perceived 
smells from a distance without contact When we have 
a medium for the sense-organ, it is reasonable to suppose 
we do not receive all our impressions at once, excepting 
in the instance of light, on grounds already mentioned. 
And sight is also excepted on the same grounds, for light 
is the cause of sight. 


Another similar problem touching sensation arises here, 
viz. whether or not it is possible to experience two 
sensations at one and the same moment of time, supposing 
it to be true that the stronger stimulus always displaces 
the weaker. For this reason, persons do not see an object 
that falls upon the eye, if they chance to be deep in thought, 
or exercised by fear, or listening to a loud sound. Let 

2 this serve as a fundamental truth and let us also observe 
that it is easier to perceive what is simple than what is 
mixed, e,g. it is easier to taste unmixed wine than mixed, 
and so with honey and colour, and it is easier to dis- 
tinguish the highest note when taken alone than when 
heard in accord with the octave, because the two things 

3 obscure each other. This occurs in cases where a unity is 
produced from several elements. If, then, the stronger 
displaces the weaker stimulus, it must happen, in case 
they are simultaneous, that even the stronger stimulus 
becomes weaker than it would be if it were perceived 
alone. For the weaker when mixed with it detracts 
from its clearness, supposing it to be true that every- 



thing taken simply is more accurately perceptible. If 
the two are equal neither one will be perceived, for they 
will counteract each other equally. But it is impossible 4 
to have a simple sensation. Consequently, we shall have 
either no sensation at all or a new one fused out of both 
elements. And this appears to be what actually happens 
with mixed elements, so long as they are mixed. Since 5 
a fusion of certain things is possible and of others not, 
the latter are such as fall within the province of different 
senses. (For where extremes are opposite, fusion is 
possible, but it is not possible to form white and acute 447^ 
into a unity, excepting in an accidental sense, not how- 
ever in the sense in which a union between acute and 
grave is possible.) It is, then, impossible to have a 
simultaneous sensation of these qualities. For the 6 
stimuli being equal destroy each other, since a unitary 
stimulus is not derivable from them. If, however, they 
are unequal, the stronger stimulus produces the sensation ; 
for the soul more readily perceives two stimuli simul- 
taneously when only one sense is concerned in the single 
act of sensation, as e.g, acute and grave. For simul- 
taneous sensation on the part of a single sense is more 
easily attained than is the action of two senses, such as 
sight and hearing. But it is not possible to perceive 7 
two things simultaneously with one sense unless they 
are fused. For the fusion will form a unity and a single 
sense can perceive a single thing and the single sensation 
is a chronological unit. So then one necessarily 
perceives fused stimuli simultaneously, because they are 
perceived by a sense-process which in actuality is single. 
The single sense in actuality perceives a numerically 


fiingle object ; the single sense in potentiality perceives 
a specifically single object.^ If the sensation, therefore, 
is in actuality single, it will interpret the sense-object 

s as a single thing. The sensations must then be 
fused. When they are cot fused, the sensations will 
be in actuality two. However, there must be a single 
actuality which corresponds to a single potentiality 
and a single moment of time; for the stimulation and 
exercise of a single sense is once for all single and its 
potentiality is single. It is consequently impossible to 

9 perceive two objects at one time with a single sense. 
But if two objects that fall under a single sense cannot 
be perceived simultaneously, this is plainly much less 
possible when they fall under two senses, as e.g. white and 
sweet.^ For the soul seems to denote what is numerically 
one not otherwise than in terms of simultaneity; the 
specifically one in terras of the discriminating sense and 
10 the character of the thing. By this I mean that white 
and black, which are specifically different, are supposedly 
discriminated by the same sense ; also sweet and bitter 
are discriminated by the same sense, although a different 
sense from the former one. On the other hand, the 
method of perceiving opposites is different, while co- 
ordinated pairs are perceived in the self-same manner, ».g. 
just as taste perceives the sweet, so sight perceives the 

' Actiul aeowtiOD concenu ifalf a given quftlit;, t.g. white ; potential 
BensatioD, qd the other hand, concema a giveD kind of qnalilj, t.g. 

' Ariatotte coDcluden chat the only way in which aevcral aensatiODS 
may be simultaneonaly eipiirieDced ia by their fusion. By the proceai 
of fusion, however, they are reduced to unity and the aenae expelienoe 
ii DO longer manifold but unitary. 

^^^ divi 



white ; aa the sense of eight perceives the black, so the 
former sense perceives bitter. Further, if the sense- 448* 
processes of opposites are opposite to each other, and if it n 
is impossible for opposites to coexist in the same in- 
divisible thing, then where opposites fall under a single 

ise, as e.g. sweet and bitter, they cannot be perceived 
jlimultaneously. And similarly it can be proven that la 
things which are not opposites cannot he simultaneously 
for some colours partake of white and others 
of black and this applies equally to other sensatioDS, e.g. 
amongst flavours certain ones have the character of sweet 
and others of bitter. Neither can fused objects be 
simultaneously perceived, for their ratios have the 
character of contrariety, e.ij. the octave and the fifth, 
unless they are perceived as one. In this way and not "3 
otherwise a single ratio of extremes is produced. For in 
■any other case there will be produced at once the ratio 
of the many to the few, and of the uneven to the even, 
and on the other hand the ratio of the few to the many, 
uid of the even to the uneven. If co-ordinates which 14 
&re specifically different, are further removed from each 
other and differ more than things that are specifically the 
Bame {e.ij. sweet and white I mention as co-ordinates, but 
specifically different), and sweet differs from black more 
than white does, it would be still less possible for these 
opposites to be perceived simultaneously than it would 
be for opposites specifically the same. So that if the ■$ 
latter are not simultaneously perceptible, neither would 
tlie former be. 

In regard to the opinion of certain writers who treat 
the subject of harmony, and say that sounds do not 

190 Aristotle's psychology dbsbksu 

really reach us at the same moment, but only appear to 
do so and we do not notice this, the time being imper- 
ceptible, the question is whether their opinion is right or 
i6 not. Here, also, one might perhaps say that we only 
appear to hear and see at the same time, because the 
intervening time is not perceived. This is incorrect ; 
it is impossible for time to be imperceptible, or for us to 
be unconscious of it, but every moment is perceptible.^ 

17 For when one perceives one's self or something else in 
continuous time, it is impossible for one to be then 
unconscious that one is; but if there is in continuous 
time a moment of such duration that it is altogether 
imperceptible, it is evident that one would then be 
unconscious of one's own existence, or would not 
know whether or not one sees and perceives. Further, 

448 b even if one has perception, time would not exist and 
there would be no object nor any moment in which 
sensation should take place, unless it were in the sense 
that one sees in a part of time or a part of the object, if 
there is a measure of time or object, which, owing to its 
smallness, is totally imperceptible. For if one sees the 
entire earth, one also perceives time itself in its 
continuity, and not in any of its isolated moments. Let 

18 C B represent a time-division in which one has no 
perception. One sees, then, in a particular part of the 
whole or sees a particular part, just as one sees the 
entire earth, viz. by seeing a definite part of it, and how 
far one walks in a year, viz. by seeing how far one 
walks in a definite part of a year. But in the division 
B C there is no perception. Now, by virtue of 

^ On the * minimam visible ' aee Lewes, Aristotle^ p. 25.3. 


perceiving the whole A B in some definite part of it, 
one is said to perceive even the entire earth. And 19 
the same reasoning holds good of A C. For one always 
perceives in a part and a part, and it is impossible 
to perceive the entirety. And so every thing is per- 
ceptible, bat one does not see what its extent is. 
For one sees the magnitude of the sun and of the 
four-cubit measure from a distance ; they are not 
seen, however, in their real size, but sometimes they 
seem indivisible, and one does not see the indivisible. 
The reason for this has been stated in the foregoing. 20 
One concludes from this that there is no imperceptible 

We must take into consideration the above-mentioned 
problem, whether or not it is possible to have several 
simultaneous sensations. By 'simultaneous' I mean such 
as are experienced in the same part of the soul and in 
one indivisible moment of time. In the first place, then, 21 
is it possible that the sensations be simultaneous in the 
sense that they are experienced in different parts of 
the soul, and not in one indivisible part, though by 
parts which are indivisible in the sense of forming a 
continuous whole? Or, to take first what affects the 
single sense, as e,g, sight, shall we say that if different 
colours are sensed by different parts of sight, it will 
then have several parts specifically the same ? For its 
repeated sensations belong to the same species. But 22 

^ Aristotle defines time (note 2, p. 1S3) as the measare or number of 
motion, but time cannot exist apart from mind, as number cannot exist 
apart from a calculator, and the sole calculator is mind {Phy», 223a 
16 ff.). 

^ Read ra^d (supported by moat of the M88. ) for raOreu 



if one says that, as in the instance of our two eyes, 
a certain unity and single activity is produced, bo 
nothing prevents our regarding the soul in the same 
way. If, however, the combination of both forms an unit, 
then that which is perceived will be an unit, and if they 
remain uncombined, then the result will likewise be 

23 uncombined. Again, the same sensations will be mani- 
fold, in the sense in which one speaks of sciences aa 
44911 manifold. For neither ia there any actuality apart 
from its corresponding potentiality, nor is there any 
sensation apart from actuality. If one does not experi- 
ence simultaneously the sensations which occur in a 
single indiWsible part of the soul, it is clear that one does 
not experience others simultaneously For it is simpler 
to perceive these several things simultaneously than it is 
to perceive generically difi'erent things simultaneously. 

34 But if the soul senses sweet with one part and white 
with another part, the derivative of these two is either an 
unit or it is not an unit. But it must be an unit, for < 
the perceiving organ ia an unit. What b the unit, then, ' 
with which this organ is concerned ? For we have no 
unit from sweet and white. There must, therefortL-lw 
some unitary principle in the soul, whereby it perceives 
things as wholes,' as remarked above, but things generic- 
ally difl'ereut are sensed by different organs. Is then 

as the principle whereby we perceive sweet and white a 
single organ, in so far as these qualities are united, 
but when they are actually isolated, ia it a different 

' TluB f unotjon li Mcribcd u 
experiences of the indiviilual ii 
percept. Cf. liUrodtieliott, Chap. 

the 'common » 


organ that senses each of them? What applies to 
the things themselves, applies similarly to the soul. 
For numerically one and the same thing is white and 
sweet, and possesses many other qualities, unless the 
qualities be regarded as isolated from one another, and 
yet the essential nature of each quality is different One 
must likewise conclude in reference to the soul that one 26 
and the same principle (numerically regarded) perceives 
everything, although its mode of expression is different, 
in some cases generically different, and in others 
specifically different Simultaneous sensations, therefore, 
are experienced in one and the same principle of the 
soul, but not in one and the same relation to this 

It is evident that every sensible object has a certain 
magnitude, and that it is impossible to perceive what 
is indivisible. There is a point from which it is im-27 
possible for one to see, viz. a point of infinite removal, 
but the point from which vision is possible is deter- 
minate. The same applies to the odorous and audible 
and to such sensations as are not tactuaL There is an 
extreme point of remoteness from which vision is no 
longer possible, and a point of nearness at which vision 
begins. This point must be indivisible, and what is 28 
beyond it is not perceptible, and what is on this side 
of it must be perceptibla If, indeed, an indivisible 
thing is perceptible, then it will follow when one places 
it at the extreme point from which it is no longer 
visible, and again at the point where perception begins, 
that it is simultaneously visible and invisible. And this 
is impossible. 

194 Aristotle's psychology dbsbnsu 

449^ We^ have now treated, in general and in particular, 
the subject of the organs and objects of sensation. In 
what remains, we must first investigate the subject of 
memory and of memory's process. 

^ Bekker in the editiona of Berlin (quarto) and of Oxford (octavo) 
transfers this paragraph to the beginning of the tractate On Memory, 
For a critical examination of the arrangement of the text vidL 
Freudenthal in Rhtin, Museum, Vol 24, p. 393. 



In regard to memory ond its process, we must determine 
what its nature is, by what agency it is produced, and to 
what psychical organ the phenomenon of memory, as 
well as that of recollection, is to be ascribed. For 

^ Aiistotle makes the following distinction between memory {fivijfifi) 
and recollection (dwdftmjais) : the former is the reproduction of a past 
experience accompanied by the consciousness that the experience has been 
previously had ; the latter is the deliberate reproduction of the same 
experience and is based on reflection. The former is possessed by the 
lower animals and the latter by man only. Plato had already made a 
distinction between memory and recollection (PhaecU), 73 B ff., 
Philebys, 34 B). The passive presence of residual sensations in the soul 
is memory, while their active recall to consciousness is recoUection. In 
the Meno the whole of knowledge is resolved into recollection or 
reminiscence {dvdfuni<ris), learning being only the stimulation or revival 
of knowledge congenitally in us. In a note which Grote meant to be 
added (directions to this effect are recorded in the ua. ) to Chap. XX. 
of his PlcUo and the Other Companions of SokrcUea, he says : '' The 
doctrine of Reminiscence declared and illustrated by Sokrates in the 
Platonic Menon {rSura fui^<ri$ dydfuftiffis) bears much analogy to the 
Development-Hypothesis espoused by Mr. Herbert Spencer ; an extension 
and special application of the large views opened by Mr. Darwin respect- 
ing the origin of species. Each individual animal is assumed to begin 


196 Aristotle's psychology di imc. 

the same persons are not endowed with good memory 
and good recollection, but as a rule phlegmatic natures 
remember well, while the quick and ready-witted are 

2 apt at recollection. 

First of all we must grasp what is understood by the 
object of memory. For one is often mistaken about this. 
The future cannot be the object of memory; this is 
rather the object of conjecture and expectation (and we 
might even have a science of expectation, as some 
describe the subject of prophecy). Neither can the 
present be its subject-matter, for our senses are concerned 
with this. By sensation we do not have cognizance 
either of the future or of the past, but only of the 

3 present. Memory, on the other hand, regaids the past. 
No person would say that he remembers the present 
while ^ it is present, e^. that he remembers seeing the 
white object while he sees it ; neither does one remember 
the object of contemplation, so long as the act of con- 
templation and thought continues. But one merely says 
that in the former case one sees, and, in the latter, one 
knows. When, however, one possesses knowledge or sen- 
sation which is not in actuality, then one remembers that 
the angles of a triangle are equal to two right angles, 
because one has learned it or thought it out, or, on the other 

existence with a large stock of congenital predispositions and aptitudes 
engrained in its nervous system as the result of an ' infinitude of past 
experiences ' — ^not indeed of its own but of its progenitors. Hence arise 
aU its instincts, and many of its mental combinations which go beyond 
instinct. See Mr. Spencer's Psychology, pp. 577-583-619." Extract 
from the mss. of "Grote's Papers" in the Bodleian Library, Oxford 
(MS. add. D. S5, p. 37). 

^ Read 5rc for Sn. 



^^^ futui 


hand, has merely heard it or visually observed it, or found 
it out in some such way. For when memory actually takes 
place, one must say that the process in the soul is suob 

that one formerly heard, perceived, or thought the thing. 
Consequently, memory is neither sensation nor conceptual 4 
thought, but it is the condition or modified form of one 
of these, after the lapse of time. There is no memory of 
the present in the present moment, as we have said, but 
there is percepLion of the present, expectation of the 
future, and memory of the past. Consequently, all 
imory is associated with time. Therefore, only those 
.tures that have perception of time, have memory, 
and memory attaches to that organ whereby time 
is perceived.' Now we have already discussed imagin- s 
alion in the treatise On the Soul^ and we concluded 
there that thought is impossible without an image. For 
we find in thought the same conditions as in drawing 4500 
figures. In the latter without needing a triangle of a 
definite magnitude, we nevertheless draw a triangle of 
definite size. So, too, the thinlcLng mind, even if it does 
not think a magnitude, still places a quantitative body 
before its eyes, although it does not think it as such. If 6 
it is the nature of the quantitative in an indefinite sense 
•with which the mind is concerned, then thought represents 
'ft under the form of a definite quantity, but thinks it 
merely as quantity. The reason why it is impossible to 
think anything apart from continuity (even things that 
are not subject to the laws of time cannot be thought 

' The orgui of memorj and the oi^ui whereby w 
0«DtnU orgaa or heut (4Sla 17). 

'Cf. Dt an. *276 14 ff. ; 434a ff, ; 431a 17. 

198 Aristotle's psychology de 

without time^) is a problem that belongs elsewhere.' 
We must be conscious of magnitude and motion * by the 
same faculty whereby we are conscious of time. An 

7 image is a product of sensation in general. Evidently, 
therefore, the cognition of these things is to be ascribed to 
the primary power of sense. Memory, even the memory 
of concepts, does not take place without on image. 
Consequently, memory concerns the faculty of thought 
accidentally and the primary power of sense intrinsically.* 
It is, therefore, possessed by other animals, and is not 
peculiar to man and creatures endowed with opinion 

8 and thought. K it were a property belonging to the 
conceptual powers, it would not be found in many 
animals outside of man, perhaps in none of the brutes, 
seeing that they do not, as a matter of fact, possess 
it because they all lack the sense of time. For in 
an activity of memory, as we remarked before, there is 
always the additional consciousness that one has seen or 

9 heard or learned this in time past. Prior and later are 
properties of time. In reply to the question to what part 
of the soul memory is to be ascribed, it is plain that it 
belongs to the same part as imagination. The objects of 

^Aristotle is referring probably to the heavenly bodies and their 
eternal laws. 

'Topics of this kind Aristotle refers to the First Philosophy or 

' Magnitude and motion are classified by Aristotle amongst the ' com- 
mon sensibles' and as such they are perceived by the 'oonmion sense' 
whose organ is the heart. 

4 In other words memory is a revived sense-experience and is due to 
the direct function of the primary organ of sense (the heart) ; it oonoems 
the faculty of thought only accidentally, viz. in furnishing it with 
images which are converted into concepts that are essentially different 
from images. 


memory, intrinsically, are the same as the objects of 
imagination; accidentally, they are such objects as are 
impossible without imagination.^ 

The question might be asked: How in the world is 
it that while a mental impression persists, although the 
thing itself is no longer at hand, one remembers what is 
not present ? Evidently we must regard this phenomenon lo 
which through the mediation of sensation is produced in 
the soul and in that part of the body^ which possesses 
sensation (whose persistence we call memory), as similar 
to a painting. For an active stimulus stamps on the soul 
a sort of imprint of the sensation, analogous to stamping 
with a seal-ring. For this reason, too, persons who are n 
deeply moved by passion or by the ardour of youth do 450 3 
not remember, just as if the effort and the seal were 
applied to running water. In other persons, because of 
their worn-out condition, like old buildings, or because 
of the hardness of their receptive principle, no impression 
is made. Consequently, the very young and the aged have 12 
poor memories. For the former are in a fluent condition 
owing to their growth, and the latter are unstable owing 
to their decay.^ Likewise the excessively quick and the 
excessively slow seem to have poor memories. The 

1 When the objects of imagination are recognized as past experiences 
or copies of past sensations they are called memories. They are, there- 
fore, in their essential nature or intrinsically the same as the objects of 
imagination. Objects of memory in an accidental sense are, perhapfl, 
such elements as do not attach to the image as such, but are not possible 
without it, e.y. the ciroomstance that Coriscus (who is the image proper) 
was a native of Scepsis. 

* Namely, in the heart. 

>It is this passage which Raid distorts in his review of Aristotle's 
theory of memory. Ct Works, ed. Hamilton, p. 353. 



former axe too moist aDd the ktter too bard. Con- 
sequently, 'the image does not last in the soula of the 

13 former, and in the latter it does not fasten. If such is 
the truth regarding memory, the question arises whether 
one remembers the impression or the thing from which 
the impression was derived. For if it is this impression 
of ours which ia the object of memory, then we do not 
remember what is absent On the other band, if it is 
the thing that we remember, how does it come that while 
we perceive this impression we remember what we do not 
perceive, viz, the absent thing?^ And if memory is 
analogous to an imprint or picture within us, why should 
the perception of precisely this thing be the memory of 
aomething else, and not the memory of just this picture 1 

■4 For it is this impression which one contemplates and 
perceives iu actual memory. In what sense then does 
one remember what is not present ? It would then be 
possible to see and to hear what is not present. Or is 
there a sense in which this is possible and in which it 

15 actually occurs ? For example, the animal in a picture 
is both animal and a copy, and both of these are one and 
the same thing ; but the mode of existence in the two 
instances is diETerent, and it is possible to regard this 
picture both in the sense of animal and in the sense of 
image, and so it is with the image within us : we must 
r^ard it both as something in itself and as the imi^e of 
something elsa In so far as we regard it in its own 

'Aristotle exploini further down (4001' 30) that the imiLge is not oolj 
a thing in itdolf which we bav« actailly in conaciousneaa, hat it is aUo 
ropresentfttive of the eitemal and absent thing, which, though not In 
oODSoiDUBnaBB, ia thus mediately or repreBentatively remeubered. 



nature, it is an idea or a mental representation ; in so far 
as we regard it as belonging to aometliing else, it is a copy t6 
or a memory. When, therefore, an actual stimulation of 
this image takes place, and when the soul perceives it in 
its own nature, it appears to come to expression as an idea 
or a phantasm; if however the soul regards it as belonging 
to something else, then, as in the case of a painting, the 
soul contemplates it as a copy and as the picture of 
Coriscus, without having ever seen him. The point« 
of view here and in the case of our regarding a painted 
animal merely as an animal are different : what arises in 
the soul ia the latter case is purely a thought ; in the 45'" 
former case, because the object is there regarded as an 
image, it appears as a memory. And, consequently, there 17 
are times when we do not know, regarding such psychical 
processes due to earlier sensations, whether they are 
produced by sense-experience, and we are in doubt 
whether they are a memory or not,' At another time it 
happens we think and recall that we have heard or 
known the thing in the past. This takes place when 18 
after contemplating a thing in its own nature, one shifts 
one's position and regards it as the copy of another thing. 
The converse of this also happens, as is shown by the 
case of Antipheron of Oreos and other ecstutics. For they 
asserted that their phantasms were real, and that they 

' It is often difficult to decide whetheT certain apparent m 
merely fictionB of im&guiatioa or actual paat eiperiencei, becaiue 
imagiiiBtioli U not merely reproductive [alaBrfriii^) but productive 
(XoYuTTtxi}), It is, however, imponible to have an □nconscioua memory. 
So long BH one ii not coiiBcioiu that h given eiperieDi:e or image has 
been had before, the Uiiog is only a pblmtaam (^drriur/w) and not • 
memory (prritiiriviia). Cf. 452b 26. 

202 Aristotle's psychology db 

remembered the things. This phenomenon occurs when 
19 one regards as a copy that which is not a copy. Exercise 
in repeatedly recalling a thing strengthens the memory. 
This, however, is nothing more nor less than the frequent 
contemplation of a thing as a copy and not as an object in 
itself. The nature of memory and of its process has now 
been explained as the persistent possession of an image^ 
in the sense of a copy of the thing to which the image 
refers, and it has been further explained to what faculty 
in us this belongs, viz. to the primary power of sensation, 
and to that organ whereby we perceive time. 


The subject of recollection remains to be treated. First 
of all we must take as presuppositions the truths which 
were established in the treatise On Argumentation} 
Accordingly, recollection is neither the recovery nor 2 
acquirement of a memory. For when one learns or 
acquires an impression for the first time, one does not 
recover any memory (for none has preceded), nor does 
one acquire an initial memory. But when a persistent 
mental condition and impression is fixed in the soul, then 
we have memory. Consequently, memory is not produced 
simultaneously with the production of an impression. 
Further, in the indivisible complete moment when the 3 
impression is first received, the impression and the know- 
ledge are recorded in the afiected subject, if one can call 
this mental condition and impression, knowledge, (and 

^Themifltins and Michael Ephesius think the reference is to the 
ProhUmcUa, Bonitz, however, oonaiders it more probable that Aris- 
totle is referring to the droplcu diBCoased in Ch. I. of the present 
tractate. Cf. Index to Bekker's Berlin edition avb, vac, 'AptoTorAiyf, 
99a 38. If the latter supposition is correct^ one wiU have to give the 
words X^oc inx^ifni/MTucQl the nnnsual meaning of JniHal Treaiiae, 
which, however, they might perhaps bear. 


204 Aristotle's psychology dbm»m. 

there is nothing to prevent our remembering, in the sense 
of accident, a certain thing which we know conceptually). 
But memory as such is not possible until after the lapse of 
time. For what we remember now, we have previously 
known or experienced, but what we experience now is 

4 not in the present moment remembered. Further, it is 
451 6 evidently possible to have in memory what we do not 

now recollect, but what was once perceived or experienced. 
When one re-acquires knowledge or sensation (or whatever 
the mental possession be to which we apply the term 
memory), it is then that one recollects one of the afore- 

5 said mental possessions. The process of memory takes 
place, and memory ensues. Neither do the phenomena 
of recollection, if their occurrence is the repetition of a 
previous recollection, follow absolutely the same order, 
but sometimes they occur in one way and sometimes in 
another.^ It is possible for the same individual to learn 
and discover the same thing twice. SecoUection, then, 
must differ from learning and discovery, and there is 
need of greater initial latitude here thcui is the case with 

6 Recollection is effected, when one suggestion succeeds 
another in natural order. If the succession is a necessaiy 
one, it is plain that when the antecedent suggestion is 
given, it will excite the succeeding one. If, however, the 

^ A given association may at one time awaken a recollection and at 
another time faU to do so (cf. 4526 1 ff.). 

s In the case of learning and discovery there is a definite and exact 
process by which a given result may be twice arrived at. In the case 
of recollection, on the other hand, there is not the same fixity of 
procedure. There are not only many forms of suggestion and associa- 
tion, but a given suggestion may not effect the same result in two 



a Dot a neceesary one, but only customary, the 
recollection will be stirred generally. But it is a fact 7 
that aome persons by being impressed only once are 
trained ^ in a given way more than others after frequent 
irapresaions. And so there are aome things which after 
we have seen once, we remember better than others do 
who have seen them frequently. When, thereforCj _we 
recollect, we awaken certain antecedent processes and 
continue this until we call up that particular experience, 
lifter which the desired one is wont to appear. That is s 
the reason why we hunt through a series in thought, 
beginning with an object presently before us, or with 
something else, or with an object that is similar, or 
opposite, or contiguous.' In this way, recollection is 
awakened. For mental movements in these instances 
are identical in some cases, in others simultaneous 
with, the desired experience, and in other cases they ' 
involve a portion of it, so that there is a small 
remainder whose stimulation ensues. This then, is 
the way in which people try to recollect, and without 9 
conscious effort they recollect in this way, when 
the desired experience is recalled as thu sequence of 
another experience. For the most part, however, the 
desired experience is recalled only after several different 
suggestions, such as we have described, have preceded. 

''Trained' {t6iir8^rai\ moanH here the acquuition of a fixed habit 
{f$at) or diBpoaition. In the oose of other |)enKina, intpresaioiu da not 
produce a fixed diapoaition, but are «TaneBceDt. CoiuequeDlly ia the 
latter, a BnggeBtion ia loeffsctive, while It reaults in recollection in 
thoae petBoni where tlia impreaion hoc become a fixity or 'habit.' 

*Tba laws of auociation, ordinarily treated aa coatiguity and 
■imilarity, are here stated by Aristotle >■ aimilarity, uoatrart, i 

206 Aristotle's psychology dbmsm. 

One does not at all need to look at the remote and ask 
how we remember it, but at what lies near before ns. 
For the same method applies to both cases, — I mean the 
method of sequences,^ without any prior effort to find 
this sequence and without recalling it. For mental 

10 movements follow one another, this one after that, 
by habituation. When a person wants to recall a thing, 
he will do the following : he will try to gain a starting- 
point in the process, in sequence to which the desired 
experience was had. Consequently, recollections which 
are awakened from the starting-point are most quickly 

452 a and best effected. For just as things are mutually 
related in their order of succession, so also are the 

11 mental processes. And such things as have a fixed 
order are easily remembered, as e,g, mathematical truths. 
Other things are remembered poorly * and with diflBculty. 
EecoUection differs from re-learning in this, that there 
can be in the former case a sort of self-movement back 
to that which follows upon the original experience. 
When this is not done, but the recollection is prompted 

12 by another person, then it is no longer memory. Often- 
times one is unable to recollect a thing, but after searching 
succeeds in finding it. This seeking and finding is what 
happens when one awakens a number of experiences and 
continues to do so until one sets that particular experi- 
ence in motion upon which the desired thing is attendant. 
Memory is the possession of an experience potentially 

^ This aeriea of Bequencea U compared by ThemiBtios to a chain, in 
which if one link be lifted the next wiU likewise be moved and so on. 
Of. Sir WUliam Hamilton's note in Reid's Works, p. 894. 

'Read ^aOXon Kal for 0aOXa. 


revivable. This process is effected, as was said above, in 
such way that it comes from the person's own effort and 
from the movements in his power. One must, however, 13 
have a starting-point. And so persons appear sometimes 
to recall things from local ^ suggestions. The reason is 
that one passes rapidly from one thing to another, e,g. 
from milk to the suggested idea of white, from white to 
air, from air to the moist, and from this one recalls the 
late autumn, which is the season one was trying to think 
of. In general, it is the middle, too, of the entire series 14 
that seems to be the starting-point for memory. For 
when a person does not remember earlier, then he does so 
when he comes to the middle point, or when he does not 
remember here, then at no other point at all, as is the 
case e,g, when one passes through the series ABCDEFOH} 
If one does not remember at J7, one remembers 
when one comes to E, provided one is in quest of F or O, 
For from that point the movement of suggestion is 
possible in both directions, towards the point D as well 
as towards the point F? If, however, a person is not in 15 
quest of one of these, he will remember on reaching C, and 

' There ia no reason for adopting the conjecture of Sir WUliam 
Hamilton (drora for 6xh r&wiav 452a 13), which Barth^lemy- Saint- Hilaire 
(Commentary, cid loc,) considers necessary and which Hamilton charac- 
terises as " absolutely certain " (Keid's Worka, p. 905 note). 

' Freudenthal {Rhtin, Museum, xxiv. p. 410) thinks we have here a 
defective text, because in a series of eight elements there is no middle 
term. It seems, however, hopeless to get anything satisfactory out of 
the iUnstration by emendation or reconstruction. 

' Ftd. Freudenthal's explanation in the Archiv fur GeschichU der 
Philowphie (vol. ii. p. 2) and Siebeck's in his UrUerauchungen zur 
Philos. der Orieehen (2te Aufl. p. 155). Sir William Hamilton simply 
distorts the text beyond recognition in order to obtain an intelligible 
translation, and even then achieves but a meagre success in his aim. 

208 Aristotle's psychology db 

if not then, he will remember on reaching A, and this is 
the ease always. But from the same point of snggestion 
one sometimes remembers and sometimes does not, the 
reason for which lies in the possibility of movement in 
more than one direction from the initial point, e.g. from £ 
i6 to jP or from JE to D. If the movement is influenced by 
an old suggestion, it takes place in the direction of the 
more fixed habit.^ For habit is second nature. Conse- 
quently, we remember easily what we often ponder. For 
as one definite thing succeeds another in nature, so it 

17 is also in our activity. Frequent repetition produces 
nature. Since we find in the realm of nature occurrences 

452^ that violate her laws and are due to chance, much more 
do we find this in the realm of custom, to which the 
term nature cannot be applied in the same sense. The 
consequence is that a movement here sometimes takes 
place in one direction and sometimes in another, especially 
when the mind is distracted from a particular point to 

18 something else. Therefore, when one has to remember a 
name, and remembers one like it, one commits a solecism 
in regard to it. This then is the way in which recollec- 
tion takes place.* 

The most important thing here is the necessity of 
appreciating time, whether in a determinate or an in- 

19 determinate form. There must be some power whereby 
we distinguish a longer from a shorter interval. It is 
natural that the same conditions which apply to magni- 
tudes, apply here also. For we think what is large and 
what is remote in space, not because thought extends to 

» Vid, SuUy, The Human Mind, Vol. I. p. 201. 
' Namely, through the aetocUtion of id< 




the given point, as some say^ in their explanation of 
vision (for we can think the non-existent as well as the 
existent), but because of an analogous process in the 
mind. For the figures and processes that correspond to 
things are in the mind itself. What difference will it 20 
make, then, whether one thinks what is larger, or the other 
class of things that are smaller? For all the internal 
elements are smaller, and the external have, as it were, a 
proportional magnitude to them. It is perhaps in the 
case of distances in space just as it is with figures, one 
has to assume the possession of another analogous figure 
in the mind itself. So, e,g. if one draws the lines AB and 21 
BE, one produces CD, for AC and CD are proportional. 
Why does this produce the line CD rather than FQ'i 
Or is this due to the fact that as AF is to AB, so ^ is to 
Ml For these lines are drawn at the same time. And 
if one wants to think the line FQ, one thinks similarly 
the line BE, and instead of HI one thinks KL. For 
these are related to each other as FA to BA? 

^ Empedooles. 

'Frendenthal {Rhein. Mtueum, VoL 
24, p. 416) attempts to elucidate this 
hopelessly difficult passage by the 

In this figure Freudenthal makes AB, 

BE represent sense-impressions; AFf 

FO external objects ; AC, CD, notions 

or concepts ; MH, HI, time objectively 

regarded ; AfK, KL, time subjectively 

regarded. Consequently, so he goes on 

, . AB AC AF ^, ^ 

to explain: ^^=^7^=-^ means that 

presentations of sense or images of 
^arraaia are related to each other as the 



M When the suggestion of the thing and the Buggestion of 
time coincide, we have actual memory. When, however, one 
believes one does this without really doing it, one only 
believea that one remembers. For there is nothing to 
prevent one's being deceived and fancying that one 
remembers without this being actually the case. In 
actually remembering it is impossible that one Bhoald 
not believe one is remembering, but should be uncon- 

23 scioua of it. For this is just what constitutCB memory. 
If, however, the suggestion of the thing and the sug- 
gestion of time are separated from each other, then no 
memory is awakened. The suggestion of time has a two- 
fold meaning. Sometimes a thing is not remembered 
in determinate time, e.g. that day before yesterday one 

453 a did something or other ; in other instances one remembers 
in terms of time-measure. Memory, however, takes 
place even if one does not remember in the latter way. 

24 People are wont to say that they remember, although they 
do not know just when a thing happened, in cases where 
they are ignorant of the determinate measure of the 

We have already said that the same individuals are 
not endowed with good memory and good recollection, 
as Eecollection differs from memory not merely in the time- 
element, but also because many animals share the endow- 
ment of memory, while none of the known animals, one 

correaponiiing n 


are related to each other and the cDrresponiliag eitemBil objccta are re- 
AF H FO HI ...,., , II.-, 

luted to each otber 

E related to theiT s 

e-lmpreuionB as objective titae to EubjeotiTe 




may say, excepting maD, is endowed with recollection. 
The reason for this is that recollection is a sort of ayllo- »6 
gistic proceas. In recollection one reasons that one has 
known or beard or had some such experience of the thing 
in question, and the process is a sort of inquiry.' And 
this is naturally found only in those creatures which 
have the power of deliberation, and deliberation is a kind 
8yll<^stic procedure. 

That tbis condition affects the body, and that reeollec- 17 

ion is the search for an image in a corporeal oi^an,* is 

ived by the fact that many persons are made very 

itleas when they cannot recall a thing, and when quite 

libitlng' their thought, and no longer trying to remem- 

', they do recollect nevertheless, as is especially true of 

le melancholic. For such persons are most moved by 

images. The reason why recollection does not lie within 28 

our power is this : just as a person who has thrown an 

object can no longer bring it to rest, so too one who recol- 

;t8 and goes iu search of a thing, sets a corporeal some- 

ling in motion, in which the desired experience resides. 

Especially disturbed are such persona as have moisture 19 

about the region of sensation ; for they do not easily come 

to rest after being stirred into motion, until they attain 

the thing sought for, or the movement has taken its 

proper course. Consequently, the feelings of anger and 

Id intentiniial recollection one empLoya the laws of uwociiktioii 
^alibentely and through rsSection ; in spontuieous recoUeation the 
Mine laws »pp!y, bnt are not deliberately employed. 

Id recoUectioD the organic procesa is tiara within to tbe nrguu of 

le, ff hile in tensatjoa the prooeu is from the periphery to the ceotre 

: an. 4066 17). 

'Read, > 

a 17. 

212 Aristotle's psychology dxium. 

fear, when they once set up a movement, do not cease 
although opposing movements are started agapst them, 

30 but on the contrary persist towards their own aim. 
This affection resembles names, melodies, and words, when 
these are given violent utterance. For after one has 

31 ceased, the singing or speaking recurs involuntarily. 
Further, those whose upper body is too large, and also 

453 ^ dwarfish persons, have less power of recollection than those 
of the opposite physical structure, because the former are 
too heavy about the organs of sensation, and because the 
initial movements cannot persist but are destroyed, and 
direct movement in the process of recollection cannot 

32 readily take place. Also the exceedingly young and the 
very old do not recollect well on account of their move- 
ment ; for the latter are in decline, and the former in 
rapid growth. Furthermore, children are like dwarfs 
until they advance in age. 

We have now treated the subject of memory and its 
process, its nature and the psychical organ whereby 
animals remember ; also the subject of recollection, in its 
nature, its forms, and its causes. 



We most now consider the subject of sleeping and 
waking, and ask what they are and whether they are 
phenomena peculiar to the soul or common to the body ^ 
and the soul, and if they are common, we must further 
inquire to what particular organs of the soul and body 
they belong. Further, we must inquire to what cause this 
animal function is due and whether all animals share in 
both sleeping and waking. Or are certain animals endowed 
with the one, and others exclusively with the other, or 
are there creatures that are endowed with neither of 
them, and others with both ? In addition to this we must 
investigate the nature of dreams and explain why persons 
sometimes dream ^ in sleep and at other times do not. 
Or shall we say that dreaming always occurs in sleep, 

^ AriBtotiehad himaelf stated the mixed phynological and psychological 
character of these opuscules in referring to their suhject matter as cou^d 
r^t f vx^ '"^ ffti>fJuiTot (43Sa 7). See also note, 1, p. 145. 

^The suhject of Dreams and Prophecy hy Dreams is specially treated 
in separate opuscules. Vid, pp. 231 ff., 247 fL 




but we do not remember our dreams ? If this is true, 
what is the explanation ? A further question is whether 
or not it is possible to foresee future events, and if it is 
poBflible, in what sense are they foreseen ? Further, is it 
possible to foresee only such future events as are per- 
formed by man or also such as are caused by divine 
power, and does this foresight apply to what takes place 
in the course of nature or to the results of accident ? 

2 First of all it is evident that both sleeping and waking 
are to be ascribed to the same organ, for they are contrary 
functions, and sleep is clearly the negative of waking. 
Now contraries, whether in the realm of nature or else- 
where, are always expressed in one and the same organ 
capable of receiving them and are affections of the same 
thing, I mean e.g. health and disease, beauty and ugUnese, 
strength and weakness, sight and blindness, hearing and 

454 a deafness. This ia further evident from the following : it 

3 is by the same sign that we recognise a person awake 
and one asleep. For when a person has sensation we 
regard him as awake and we believe that every waking 
person has sensation to a certain extent either of the 

4 external world or of internal processes. If, then, waking 
consists in nothing else than in having sensation, it is 
evident that by virtue of that organ wherewith one has 
sensation, waking creatures are awake and sleeping 

5 creatures are asleep. But since sensation is not the 
function exclusively either of the soul or the body (for 
where there is potentiality there is also a corresponding 
actuality ; but what we understand by sensation in its actual 
sense, ia a psychical process mediated by the body), it is 
plain that this phenomenon does not belong exclusively 



1 the soul, and on the other hand it is impossible for an 

■inanimate body to experience aensation.' In earlier 6 

■treatises ^ we have analysed the parts of the soul as we 

Kcall them, and explained that the Dutritive part is different 

P-from the other powers iu animate bodies, although no 

other power can exist independently of it. From this it 

ia evident that such living creatures as are endowed oaly 

with the functions of growth and decay, do not ex- 

kperience sleeping or waking, as e.g. plants. For they 

Khave no organ of sensation, whether separated from or 

conjoined with the oi^an of nutrition ; — in potentiality 

and mode of expression these two organs are separable 

from one another. It is likewise true that there is no 7 

L ereature that continuously wakes or continuously sleeps, 

\ bet both these conditions are found in the same animals. 

If an animal has sensation, it is impossible that it should 

not sleep and wake. Both these phenomena refer to the 

I experience of the primary organ of sensation.* It is 
impossible that either of these conditions should be 8 
continuously found in the same creature, e.g. that any 
ipecies of aninial should sleep or wake constantly, because 
■whenever we find a natural function, as soon as the 
time is exceeded during which the function is capable of 
being exercised, the organ necessarily becomes impotent, 
just as the eye by exercising vision becomes unable to 

' 'AurfdvotMi aignifiea canaaiouaiiMB as well &s the phyBtologJc&l 

"Cf, De on. 415a 23 ff. ; 43a. 23 ff. ; A^iaSSL 

'Namely, the heart. Pluits have on coolral organ [Dt an. 1116 19), 
which U neceiaarj to senBation, sad withaat the Utter they cannot b« 
■aid to Bleep or wake. Bleeping and waking being reapectivel; ths 
Mtivitj' and quieaoence of Bensation. 



perform this function. The same thing applies to the 
5 haud, and to every other functioning oi^an. Now, if 
there is an oi^n to which the function of sensation 
belongs and the time is exceeded during which con- 
tinuous sensation is possible, then the organ will become 

10 powerless and no longer perform its function. If, there- 
fore, waking is defined in terms of this condition, viz. as 
the release of sensation from a state of impotency, and 

454* if of two contraries one must always be present and the 
other absent, and if waking is the contrary of sleeping, 
(and, consequently, one of the two must in every case be 
present), then sleep would be necessary. Consequently, if 

11 this is the nature of sleep, and it consists in a loss of 
power through excess of waking, and excessive waking Is 
sometimes pathological and sometimes normal (so that 
the incapacity and its recovery would also have the 
character of the pathological and normal), it follows that 
every waking creature must also sleep. For continuous 
activity is impossible. So, too, there is no creature that 

II can sleep continuously. For sleep is a condition of the 
sense-organ which is like being fettered and held im- 
mobile. Every sleeping thing, therefore, must have a 
sense-organ. By sense-organ we mean that which has 
the capacity of actual sensation. But to have actual 
sensation in its proper and strict sense and to sleep at 
the same time is impossible.' All sleep, then, must be 
a condition from which waking is possible. Almost all 

13 animals, whether their natural abode is the water, air, or 


'"Un the whole, tha qanrrel bctweeo Deacartes and Locke aa 10 
whether the miiiil ever sleeps is less near to solDtJciD tlum ever." 
James, PrindpUt 0/ Pn/choloi/y, vol. i. p. 213. 


land, evidently have the power of sleep. For we see all 
varieties of fishes and molluscs sleeping and every other 
variety that has eyes. Also, the hard-eyed animals and 
the insects evidently sleep. The sleep, however, of all 
such animals is brief. And consequently an observer 
may not notice whether or not they share in sleep. 14 
In the observation of crustaceans it has so far not 
been clearly established whether they sleep or not. 
If, however, the foregoing reasoning is convincing, then 
one will believe that sleep occurs in this class. That 
all animals, therefore, share in sleep is proven from 
the forgoing. For the definition of animal is given 
in terms of the possession of sensation. And we 
define sleep as in a certain sense the immobility 
and fettering, as it were, of sensation; waking as the 
delivery and release from such condition. No plant can 15 
participate in either of these conditions. For without 
sensation neither sleeping nor waking occurs. Creatures 
that are endowed with sensation feel pleasure and pain. 
And when these are felt, desire is also felt. None of 
these phenomena, however, is found in plants. A proof 
of this is that the nutritive part performs its own 
function better during sleep than in a waking state.^ 455 « 
For at this time nourishment and growth are more rapid, 
which shows that for these purposes there is no need of 
the additional power of sensation. 

^ It Ib a generaUy accepted fact that nutrition is heightened daring 
sleep, which is perhaps due to the fact that digestion daring sleep is 
more r^alar, being free from mental work or distarbance. Amcmgst 
the lower animals it is asoal to sleep after eating. Cf . Spitta, Die 
Sehlc^f- und TraumzuMande, p. 19; Combe, PhyMogy of Digution, 10th 
ed. p. 112. 


We most now inquire whj it is that sleeping and 
waking occur, and to what sense, or senses, if there are 

2 several, they are due. Since some animals have all 
the senses and others not, t,g, some do not have sight, 
whereas touch and taste are universal excepting in cases of 
abnormal creatures (and mention has made of these in 
the treatise On the SmU^), and further, since it is 
impossible for an animal in sleep to experience any 
sensation whatever, it is clear that we shall necessarily 
find this condition in all the senses during what we call 
sleep. For if an animal were to sleep in one part and not 
in another, then it would have sensation in sleep, which 

3 is impossible. Now, in every sense there is a power 
which is peculiar to it and another power which it has in 
common with others, e,g, vision is peculiar to the eye, 
audition to the ear, and, similarly, peculiar powers belong 
to the other senses. But there is also a kind of 
common power that is associated with all the particular 
senses, by virtue of which one is conscious that one 

^ De cm. 426a 10 ; 4326 23 ; 4336 31. 




I sees and heaiB, For by means of sight one does not 
I perceive that one sees, and one diflcriminates and has 4 
I the power of discrimination between sweet and white, 
1 not by virtue of taste or sight, nor by means of the 
two combined, but by means of a certain power which 
is common to all the sense-organs. For sensation is 
\ unitary and the master-organ of sensation is unitary, 
I although there is an essentially dilTerent character that 
' belongs to each category of sensation, cf/. to sound and 
I colour. This common element' is allied more nearly to s 
the tactual than to any other sense. For the tactual can 
exist apart from all the other sense-organs, but the others 
I cannot exist apart from it. This, however, was discussed 
in the atndies On the Siml} Sleeping and waking, then, 
«re evidently an affection of this common sense, and are 
consequently found in all animals. For touch is the & 
only universal sense. Now, if sleep consisted in the fact 
that all the senses undergo something, then it is remark- 
I able that in cases where it la not necessary, or in a certain 
1 sense not possible, for tbem to be simultaneously active, 
yet these same senses should become simultaneously in- 
active and immobile. On the contrary, it ia more 
plausible to suppose that they are not at rest simul- 

leously. But the explanatiou that we have given of 7 
these phenomena ia a rational one. For when the master- 
organ that rules over all the others and to which all the 

> The function ol o 
MDse, whoae organ, t 
43Sb 3a, 469a 12). Tbe follov 
that the coniiuon Miue can ( 
that both touch oaA the uomra 


wribed to the central or cominoo 
.th thaL of touch, ia the heart {Dt «cnm 
g BCDteDci.-. [d the teit, does not diean 
■t apart frum the ipeuial HUBea, but 
aeiue are ueceasary to the others. 
Vvt. also De jumiK. 46T'> 28 ff. 


4S5* others are directed, is aflected, all the subordinate organs 
ar« necessarily affected with it ; on the other hand, when 
one of the latter is disabled it is not necessary that the 

8 master-oi^an should be disabled also. But it is evident 
from many considerations that sleep does not consist in 
the inactivity and non-use of these special senses, nor in 
their incapacity to experience sensation. For this is juat 
the sort of thing that happens in swooning : swooning is 
the exhaustion of the senses. And there are also certain 
other kinds of mental disturbances that resemble this. 
Also, by compressing the jugular vein, one loses 

9 sensation. But whenever there is a loss of the use of 
sensation, it does not find its explanation in any chance 
sense nor is it attributable to any haphazard cause, but 
the explanation is found, as we just now said, in the 
primary organ of all sensation. For when this is 
disabled, all the other sense-organs are also necessarily 
unable to have sensations. When, however, one of 
these latter loses the power to act, the common sense 
is not necessarily disabled. 

We must inquire to what cause sleep is due, and what 

lo sort of an afl'ection it is. Now there are several kinds 

of cause ' (for we speak of cause in the sense of the 

I Arutotle viewa the world un<ter Che aspect of processes domiDsMd 
by two cauul principles— fnrm and matter. He conceives of the kturr 
>H potentUlity, whiuh in & world of movement passes over inUi a 
condition of Mtnality. Aotualitj is aynonymoos with form. In 
organic prouesBcs these two bhings are separable only in abstraction. 
Form repreaents the completed condition towards which matter strives. 
Form is therefore the end, or otherwise expressed, the final cause. 
Further, an the completed natiOD oF a thine, or that which a thing 
really and finally is, it is the essential or DotiooBl cause. The defi- 
nition of a thing ia its notional cause. Cause (niris) is here, of course, 
employed in a sense foreign to English naage. There ia no idea of 


r end or purpose ; again as the principle of motiou, as 
I the material condition, and as the notion or fonn). First 
r of all, then, when we say that nature acts with a 
, purpose, we mean that this purpose is some good, that 

rest is provided for every creature whose nature it is 
;, and that, being incapable of constant and coq- 
I tinuous pleasurable movement, this rest is a necessary i 
. «nd useful thing (and the metaphorical term 'rest' isw-ith 

perfect accuracy applied to sleep as repose). Conse- 
. ■ quently. sleep exists for the preeervation of animals, and 

the waking state is its final cause and purpose. For i 

sensation and thought are the final purpose of all 
I animals that possess either of these powers. These are 
I their highest activities, and the highest ia the end. 
, therefore, is a necessity for every animal. I 
I mean here a hypothetical necessity, viz. that if an i 

ia to preserve its nature, it must necessarily be 
I provided with certain things, and where these things 
I ore found, other things are involved. We must next 
I uk to what sort of bodily process and activity waking 

agency in it, at there is in all Kngliiih tneaninga of cAuao. It Bigni6e«. 
I rather, 'principle.' Further, form repreeenta the inner TVieb or force 
matter whereby it ia in constant tranaition towards the realiaation 
its end. In tbii sense form is the efficient or moviug cause. We 
hftve then form used in the various aensea of (t) final principle, [2) 
notional principle (>.«. the notion or significance of a thing), and (3} the 
efGcieot principle. Tbe first and third are conceived of as forces or 
causal agents, while the second is cause in the sense of being the source 
from which these forces issue. The two ultimate principles, then, 
which Aristotle employs for the explanation of all reality and all de- 
Telopoienta are : 

1. Form (the essential thing). 2. Matter (material condition), 

(a) End or final cau«. 
ib) MotiuD or efficient cause. 


aod sleeping are due, We must assume that the causes 
of sleeping and waking are the same or aBalogons 
in bloodless and sanguineous animals, and in the lower 
sanguineous animals and men. So that what we observe 
in the case of man, we shall have to apply to them all. 

■4 It has been already determined in other treatises that 
56a the origin of sensation is found in the same organ from 
which motion ori^natos. This organ is found in the 
middle division' of the three topical sections of the 
body, and lies between the bead and lower body. In 
sanguineous animals it is the pericardiac section, for 
all sanguineous animals have a heart, and this is the 

ij primary source of motion, and of the higher sensation.* 
Evidently the origin of movement and of breathing, 
and in general of refrigeration, is found in this section, 
and it is also evident that nature created the ot^ns of 
respiration and of refrigeration, which latter is effected by 
means of moisture, for the purpose of maintaining the 
warmth in this part.* But this subject will receive 

16 separate treatment later.* On the other hand, in the 
bloodless animals, the insects, and such animals as 
are incapable of breathing air, there is found in an 
organ corresponding to the lungs cougenital air which 
rises and falls. This is evidently true in the case of 
insects with undivided wings, such as wasps and 

*The "faigher sencatioD " sppeara to metu ■ense-perception or the 
apprehension of the 'common Benaiblei.' Cf. Introduction (cbnip. iv.) 
on the nature and function of the 'common aenie,' 

'That ii, for the purpose of maintaining normal animal beat, and 
for guarding against its exceu. 

' Vitl. the tractate On RetpiralUn. 



bees, also ia flies and similar insects. Bnt since it 17 
is impossible to originate motion without power, the 
retention of the breath generates power — breath derived 
from without in the case of respiring creatures, and con- 
genital breath in the caae of non-respiring animals (this 
B the reason why, as we see, winged insects buzz when 
I in motion, the sound being caused by the friction of the 
I air strikmg on the diaphragm of these holoptera). Every 18 
t creature experiences movement whenever a sensation, 
r whether its own or caused from without, is awakened in 
I the primary organ of sensation.' Now, if sleeping and 
I waking are aflections of this organ, it is clear in what 
I legion and in what ultimate organ, sleeping and waking 
I have their origin. There are persons who are subject 19 

to movements in sleep, and do many acts that belong to 
' the wakjog state, and nevertheless without any image 
I Or sensation. For the dream is in a certain way a 
ae-pereeption. About this we must speak later. 
I Why it is that we remember our dreams on waking, 
I while we do not remember acts done in a waking state, 
I has been explained in the Problems} 

' Motion {liritmi) is employed by Aristotle in several BenaeB. He not 
I only coDBtantly apeaka of iDteilectnal pToceases as tDotioiifi, but refers to 
ement in Bpace u motion, Tbe generia term is Kirniatt, which hai 
I the foUowing vaneUei (JfefojiA. 1069b 9; Dt an. 40Ga ]2, 43% 9) : (1) 
Qoantitadve motion, or motion in reference to magnitude (lard ^i^efoi}, 
which ugnitiea increue and decreue {aS^ifait noi tf^lmt) i (2) Qualita- 
tive motion (lard ri ecHAr), or transformation (aXXolwiriTl ; (3] Spatial 
motioo or locomotion (xard rb wov, called ipopi.) ; 14) Subatontial changa 
(fKTifSoXtl "ut' tiular), or birtb and deatructioD (ytrtaa msl ipBopA,). 
Aristotle dealorea, however, that the last named {Phya. 225a 29, 
: 235b 10) is not a proper form of motion, on the ground that tbe Don- 
listent cannot be said to experience motion. 
' The explanation bere referred to is not found in the extant ProtUcnu. 


Following upon what has been said, we have to consider 
to what occurrences the phenomenon of sleeping and 

2 waking is due and what is its origin. Now, it is plain 
that as soon as an animal has sensation, it must at once 
take nourishment and grow; food in its final state is, 
in all sanguineous animals, blood, and in bloodless animals 

456 b something analogous to blood. The blood is contained in 
the veins, the origin of which is found in the heart (a 

3 fact which is demonstrated by dissection). When food 
has been introduced from without into those parts 
intended for its reception, an evaporation takes place in 
its transmission into the veins, and here it is transformed 

4 into blood and is carried to its main organ. This subject 
was discussed in the treatise On Food} But we must 
resume it now for the sake of observing the origins of 
animal movement and of seeing to what aifection of the 

5 organ of sensation waking and sleeping are due. For 
sleep is not any random exhaustion of the power of 

^ The work On Food (xepl rfio^) appears to be referred to in 2>e an. 
4166 31, but whether or not it was actually written ia onoertain. It ia 
not in the present CorpuB of Aristotle's writings. 






I bIud 


^^^_ heavi 

1 canm 

■enaation, as said above. Senaelesaneas, choking, and 
Bwooning produce a similar esbaustion. And in some 
cases of swooning there has been found even a strong 
power of imagination. Now this creates a problem. 6 
For if it ia possible for a swooning person to fall 
asleep, then this imagination might be regarded aa a 
dream. Also, people often talk when they are in a 
deep swoon and are to all appearances dead. To all 
these cases of swooning, however, we must suppose that 
the same explanation applies. But, as we have said, sleep 7 
cannot he any and every incapacity to feel sensation; on 
the contrary this particular condition springs from the 
evaporation of food. For the evaporation must be thrown 
off to a certain extent, and then it must return and 
change again, like the ebb and flood of a shifting strait. 8 
All animal heat tends to rise ; when, however, it reaches 
the upper parts, it turns about and courses down again 

Consequently, sleep is most easily produced 
'ter taking food. For a large quantity of moist crass 9 
.tter is then carried to the npper parts. Thia by 

there produces heaviness and causes one to 
■fim asleep. But when it descends and in turning 
Uirows off its heat, then sleep ensues and the animal 
slumbers. A proof of this is furnished by the action of 
narcotics ; for they all, whether liquid or solid, produce 
heaviness, e.g. the poppy, mandrake, wine, and bearded 

el. And those who droop their heads and nod into to 

■lumber appear to be in this heavy condition ; they 

cannot lift their heads or eyelids. Sleep of this sort 

follows mostly on the taking of food. For there is then a 

strong evaporation from food. It further arises from 


certain fatiguing efforts. For fatigue tends to waste, and 
57 fl waste-matter is like indigested food, when it is not cold. 
i> Certain diseases, such as are due to an excessive amount 
of moisture or heat, produce this effect of sleep, as is the 
case, e.g. in fever and lethargy. Further, early infancy 
produces it ; for children sleep a great deal because all 

12 their food rises to the upper parts. A proof of this is 
seen in the excessive growth of the upper parts in propor- 
tion to the lower ones in early childhood, due to the tact 
that growth tends in that direction. It la to this c&nae 
also that epileptic conditions are due. For sleep is similar 
to epilepsy, in fact is epilepsy in a certain sense. And 

13 so the heginning of this condition in many cases happens 
during sleep, and while asleep persona have an attack of 
it, but not while awake. For when a great mass of 
fumes is carried to the upper parts, in descending they 
press on the veins and produce constriction of the passage 

14 through which respiration lakes place. Consequently, 
wine is not good for children or for wet-nurses (for it 
makes no difference, perhaps, whether the wine is 
taken by the children or by the nurses), but they 
should drink it thinned with water and in small quanti- 
ties. For wine contains spirituous fumes, especially 

'5 wine of dark colour. In children the upper parts 
become so full of food, that during five months of life 
they cannot turn their necks. For a great quantity of 
moisture rises to the upper parta, just as it does in the 
case of persons who are very drunk. This phenomenon 
suggests a rational explanation of the fact that the 

16 embryo remains at first quiet in the womb. Also, in 
general, persons with deep lying veins, of dwarf-like 




structure, and with large heads, are given to sleep. For 
the veins of the one class are small and so the moisture 
in its downward course cannot readily flow through them, 
while in the case of persons of dwarf-like structure 
and large heads, there is a great pressure and evaporation 
towards the upper parts. Large-veined persons are not 17 
given to sleep because of the facility for the passage of 
blood ^ in the veins, unless there be some adverse con- 
ditions present. Neither are the atrabilious especially 
inclined to sleep. For their internal parts are cool and 
80 no considerable evaporation takes place in them. 
Consequently owing to their dryness they are fond of 
eating. For the condition of their bodies is such that 
they seem to have eaten nothing. For the black bile, 18 
being in its nature cool, cools the nutritive region and 
the other parts, where this excretion of bile is potentially 
present From the foregoing, one sees that sleep is an 457^ 
internal concentration of heat and a natural reaction from 
the cause named. For this reason a person in sleep 19 
moves a great deal. From the moment that the heat 
ceases to rise, however, the person becomes cool and owing 
to the cooling the eyelids fall shut And so the upper 
and outer parts of the body are cool, while the inner and 
lower ones, e.g. the feet and the entrails, are warm. Yet ao 
one might be in doubt as to the statement that the 
deepest sleep occurs after eating, that wine and other 

^ The cironlation of the blood was, of ooane, unknown to Ariatotle. 
He knew only of its direct pasBage from the heart to the eztremitiea 
and of its movement to the brain and return. (4666 23 ; De tiuom. 4616 
7 ft). The brain, being the coldest organ of the body, performed the 
function, as Aristotle supposed, of reducing and regulating the tempera- 
ture of the blood. 

similar heating dtinkB are najvotic. To regard sleep as a 
cooling process i3 oot reasonable ; it is rather caused by 

31 heat. Or is one to suppose that analogously to the 
stomach which is warm when it is empty but as soon as 
it ia 6Iled becomes cool through its processes, so the 
channels and divisions of the head are cooled by the rise 
of evaporated matter ? Or are we to suppose that 
analogously to persons pouring warm water over them- 
selves and then suddenly shivering, so alter the heat has 
risen, the collected cold produces a chill and in this way 

21 counteracts the natural heat and drives it back ? Again, 
when a large quantity of food is taken, which drives the 
warmth upward, the stomach is cooled, until digestion 
takes place, just as fire is cooled when fresh wood is laid 
upon it. For sleep occurs, as we said, when crass 
evaporation under the influence of heat, rises through the 

23 veins to the head. When this can continue no longer, 
because an excessive mass has been carried to the upper 
parts, then reaction takes pltice and the evaporated 
matter flows back to the lower parts. Consequently 
when the rising heat is withdrawn, men sink down 
(man is the only animal that stands erect), and wheu the 
heat returns, it causes lapse of consciousness, and later 

24 awakens imagination. The explanation we have just 
given for the phenomenon of refrigeration is a possible 
one. The region about the brain, however, is the chief 
factor here, as we have said. The brain is the coldest 
part of the body, and in animals that have no brain 

35 the part analc^ous to it is the coldest part. Just 
as water is evaporated by the son's heat and. wheu 
it rises into the upper air, is cooled by the air's 



temperature, and condensed falls to the earth once more 
I in the form of water, so in the rise of heat to the 458* 
brain, the excessive evaporation is converted into viscid 
matter (for this reason catarrhal affections appear to 
come from the brain), whereas the evaporation that 
I assists nourishment and is normal, returns to the lower 
1 parts condensed, and decreases the heat. The thinness z6 
and slender structure of the veins about the brain con- 
tribute to refrigeration, and to the difficulty of their 
taking up the evaporation. This is the cause of re- 
. &igeration, even in cases where the evaporation creates 
an excessive degree of heat. Woking takes place when 17 
digestion has been completed, and the great amount of 
I heat which is crowded into a small region out of the 
suTTounding parts, has gained control ([over the cold]), 
and when, further, the crass blood has been separated 
from the purified blood. The thinnest and purest blood 
in the head, the thickest and most turbid in the 
I lower parts. The primary source of all blood is, as 18 

ve have said in this treatise and elsewhere,' the heart 
[ Between the two chambers of the heart there is a 
I middle chamber connected with both. ' The two 

■ Dc pari. an. MSb 4 ; dt juvtnt. 468A 32 ; dt rapir. il4b 7. 

^ According to Ariitotle there are three csvitiee or chambers in the 
[ heart, whioh he calb right, left, tad middle. The right cavity in the 
tvgGat, th« left one the Bmolleet, and the middle one it middle-iized. 
The right cavity in Aristotle's conception ia ideutic&l with the right 
ventricle, which he saw in a anffocated animal and in a disturbed alat«, 
BO that it appeared larger than the middle cavity [the left ventricle). 
ThiB in turn appears larger than the collapaed left anriclc, whiuh ii 
Arifllotle's left cavity. The foorth cavity or right auricle was merged 
by Aristotle Id the greut vein, because, aa Huxley says {Natare, vol. 
211. p. 2), the vena cava iulerior, the right auricle, and the vena cava 
■uperior and inDominate vein, when distended with blood, appear " to 

230 Aristotle's psychology disomno 

chambers severally receive blood from the two arteries, 
from the great artery and the aorta, and the sepa- 

29 ration takes place in the middle chamber. The detailed 
treatment of this subject, belongs, however, more 
properly to other treatises. On account of the un- 
separated character of the blood after taking food sleep 
occurs and continues until the purest element is sepa- 
rated off and carried to the upper parts, and the more 
turbid element to the lower parts. When this is accom- 
plished, sleepers are released from the heaviness caused 

30 by food and awake. ' The cause of sleep has, therefore, 
been explained as the reaction of crass vapour, which 
rises under the influence of its inherent heat on the 
primary organ ^ of sensation. Sleep has also been 
explained as the inhibition of the primary sense-organ, 
and its incapacity for function, and as a necessary pheno- 
menon (for no animal can exist apart from the conditions 
which develop its nature), and sleep ^ exists for the sake 
of preservation, for rest preserves. 

form one contmuons column, to which the heart is attached as a sort 
of appendage." Consequently, instead of a right and left auricle and a 
right and left ventricle, Aristotle distinguished only three cavities, a 
right, a left, and a middle. Of. Dt hiator, antm. 496a 4 ff. 

^The heart. 

' For the history of the various ancient theories of sleep see Spitts, 
Die SchU^f' vnd Traumzuatdnde der menachlichen SeeU^ Ttlbingen, 1SS2, 
pp. 2 ff., and Radestock, Schlafund Traum, Leipzig, 1879, pp. 240 ff. 

ON dreams; 


We must next investigate dreams and inquire first of 
all in what part of the soul this phenomenon occurs, 458^ 
and whether it is an afifection of the thinking power 
or of the sensible power. For it is solely by these two 
powers within us that we know at alL' If the use of 2 

^ Dreams are due to reyived movements originally set up by external 
stimuli as well as to immediate sense-impressions. The former are 
centrally excited, to use a modem distinction, while the latter are peri- 
pherally excited (cf. 4006 25 ff., 462a 8 ff., 463a 7 ff., 779a 14). In 
our waking state these movements are for the most part obliterated 
or obscured by stronger currents of thinking or feeling. In sleep, when 
the blood is less disturbed, these dream-movements come to clear con- 
sciousness. So it is that a bodily discomfort that is not felt in waking 
stirs a dream in sleep. It also happens that a dream may lead to action 
by day. Dreams, which are images or after-motions of sensations, are 
regular or distorted in proportion to the amount of physical disturbanoe 
at hand and the number of cross-sensations (461a 16). Aristotle defines 
a dream as "a movement in the organs of sense produced by imagina- 
tion" (462a 8, cf. 462a 28). Dreams rise to the surface of conscious- 
ness when they are released from the stronger movements that restrain 
them, just as artificial frogs rise to the surface when the salt is melted 
off (4616 16). 

•Cf. De an. 4S9a 31, 4316 20 ff. 



aight is viaion, and of hearing audition, and of sense in 
general sensatiou, and, on the other hand, if there are 
common sensibles* such as form, magnitude, number, etc., 
and particular sensibles, such as colour, sound, flavour, 
and, further, if it is impossible for any animal to see with 
its eyes closed and asleep, and if this applies equally to 
the other senses, then it is evident that we have no 

3 sensation in sleep, and so it is not by means of sensa- 
tiou that we experience dreaming. Neither are dreams 
mediated by opinion. For we not only say that an 
approaching object is a man or a horse, but also that 
it is white or beautiful, as to which qualities opinion* 
apart from sensation makes no deUvcninces, whether true 

4 or false. However, this is just what the soul does in 
sleep. For, as in waking, so in sleep, we believe we see 
that the approaching object is a man, and that it is white. 
Again, we think of otlier things along with the dream, 
just as is the case with perception in our waking state. 
For we also often think about what we perceive. So in 
sleep along with our imaginings we sometimes hsTO 

5 different thoughts. This would become apparent to 
anyone who would give attention on rising and try to 
remember. There liave been persons who have in this 
way observed their dreams, as e.g. those who try to arrange 
their deliverances in accordance with the precepts of the 
mnemonic arL^ For it often happens in their case that 
along with the dream they put something else, an image 

^Dtan. 41Ba 16. 

^De an. 42TA 20 S., Pom. Anai. 8Sb 33 B. Opinion refen to tha 
coDtiDgeut or to thkt which ma^r or mky not be tme {irirxiitntL Si ml 

'Cf. Top. 1636 tf., Df an. 427i 19. 



before their eyes, in the place in question. And so it is 6 
clear that not every image eeen in sleep is a dream, and 
what we think conceptually we regard as true or false 
through the organ of opinion. So much is clear on this 
subject that the same agency which in disease produces 
illusion while we are awake, also produces the condi- 
tion of illusion in sleep. Even when we are in sound 
health and know the truth, still the sun appears to us 
to be only a foot in diameter. But whether the soul's 7 
powers of imagination and sensation are the same or 
ditferent, in any case dreams do not take place indepen- 
dently of seeing and some sort of sensation. For illusions 
of sight and hearing occur when a person really sees and 
hears something, although not the thing that he thinks 
he sees or hears. In sleep, however, there is according 
to the foregoing hypothesis no seeing, no hearing, no 4S9o 
sensation at all. Tlie hypothesis thai there is no vision 8 
is, therefore, untrue, and that sensation experiences do 
, «xcitatioa is untrue; on the other hand, it is possible 
for sight and the other senses to undergo some change 
and things impinge on each of them to a certain extent, 
as in the sensation belonging to the waking state, though 
with a certain difference. Sometimes opinion declares 
that the seen object is false, as in the waking state; some- 
times it is held in check and conforms to the imagination. 
Evidently the afi'ection which we call dreaming does not 9 
belong to opinion or to the thinking part of the soul. 
Neither does it belong to the sense-part unqualifiedly. 
For it would tlien be possible to see and hear unqualifiedly. 
But we must consider in what sense and in what way it 
attaches to the part. Let us take this evident fact for a 10 

234 Aristotle's psychology dcdtbom, 

starting-point, that if sleep is a condition of the sensitive 
part, so is dreaming. For sleeping and dreaming are not 
ascribable to different animal organs, but to the same 
II organ. Inasmuch as we discussed imagination in the 
treatise On the Sovl^ and inasmuch as we find that the 
power of imagination is one with that of sensation, only 
that the mode of expression in the two cases is different, 
imagination being a process stimulated by an actual 
sensation, and since dreaming appears to be a form of 
imagination (for we call an imagination which we 
experience in sleep a dream, whether it is unconditioned 
or conditioned), it is evident that dreaming is a condition 
of the sensitive part,^ but of the sensitive part in its 
power to imagine. 

1 Dt an, 43nh 14, 429a 9. < Vid, Note 1, p. 231. 


We might best observe the nature of dreams, and the 
way in which they are caused, from the standpoint of 
what occurs in sleep. For sensible objects stimulate 
sensation in the several sense-organs, and the mental 
condition produced thereby is not only present during 
the active process of sensation, but persists after the 
sensation has gone. The phenomenon here seems 
to be similar to that observed in the case of thrown 
objects. For in the case of a thrown object, the 2 
movement persists although the mover is no longer 
in contact with the thing. For the moving body 
communicates motion to a certain part of the atmos- 
phere, and this in turn sets another part in motion. 
And in this way motion is caused both in the air and 
in water until the body comes to rest. One must 459^ 
suppose that something like this takes place also in 
qualitative^ change. A body that is warmed imparts 
by means of its heat warmth to the adjacent body, and 

' For Ariatoile's oonoeptioii of the variont forma of motion, see 
Note 1, p. 223. 




this in turn disbtibutes it further on until it reaches its 

3 terminal point. This, therefore, is what must take place 
in the organ wherewith we experience sensation, since 
actual sensation is a kind of qualitative change. Conse- 
quently, this condition is found in the sense-organs not 
only during the process of sensation, but also after the 
process has ceased, and in their inner depths as well as 

4 on the surface. This becomes evident when we have a 
sensation that continues over some time. For when we 
turn our senses to something else, the original sensation 
persists, as e.g. when we turn from the sun to a dark 
object. The result is that one sees nothing owing to the 
fact that the sense-process, stimulated by the light, still 
lurks in the eyes. And if one looks a long time at a 
single colour, whether it "be white or green, things appear 
to be similarly coloured wherever we turn our eyes." 

5 Again, if we look at the sun or some bright object, and 
then shut our eyes, there appears to sharp observation, in 
the direct line which vision employs, first of all a colonr 
like the actual one, which then changes to scarlet, then to 

6 purple, until it passes into blackness and vanishes. Also, 
the senses are affected in this way when they turn 
quickly from objects in motion, e.g. from looking at a 


'AriitotU refen to the familiar pheoomenoQ of 'after*Jin«gw.' 
The fact that the attention wu tixed (in ArUtotle's UloatntiOD) « 
conaiderable time, and that he mentiUDS Che 'Sight of coliiim,' ahowB 
that the reference a to 'positive af ter-inuLgfw ' and oot to 'primary 
memory imageB,' a diatinction unknown, of course, to AriBtotle. Cf. 
Sully, Ttie Human Mind, vol. i. p. 278; Jamei, Prindplu o/ Pnyckology, 
vol. i. p. 6i5; Ebbinghana. QrandzUfie der Pij/chologie, p. 344; 
Uelmholtz, Jlandlmth dtr phyKtologiicheB Optik (ed. 1867), pp. 366 ff. ; 
Waudt, Hiaitan and Animal Psychology, pp. 108 tL ; TitaheneT. 
Ej:ptrimtnlal FiyeKoltyy, vol. i, part il. pp. 48 t. 



I river, and especially from looking at swiftly Sowing 
earns. For objects at rest then seem to be in motion. 

[ And men are made deaf by loud noises, and tbeir sense 
of smell is destroyed by strong odours, and so on. This 

. evidently occurs as we describe it, 7 

That sense-oi^ans readily detect even minute distinc- 
tions is proven by the use of a mirror, concerning which 

I fact one might stop at this point to investigate and make 

I inquiries. From these inquiries it will at the same time 

I become plain that just as sight is subject to an impres- 
Bion, so it exercises an activity. When women look into g 

I a very clear mirror* after their menstrual flow, the mirror's 
surface becomes covered with a bloody cloud, and if the 
mirror is new the stain is hard to remove, hut if it is old 9 

' the removal is easier. The reason is that the eye, as we 4<^a 
said, not only receives an impr&.ssion from the air, but it 
also produces an impression and a movement, just as 
bright things do. For the eye is classed amongst objects 
that are bright and possess colour. Eyes are constituted 
in the same way, it is reasonable to suppose, as any other 

'Aucieot mirrorB were mode of paliobed metal. The phen 
here described U one of many of the old-wivea' Btoriei which Artitotle 
took ap in his treatises and to which he appears to have given credeaoe. 
AristoUe, we muit remember, hod do cjiD«iderable body of critically 
lifted and scieatifically accredited data to work with. He was depen- 
doDt ubiedy on ha own obflerratioos and tbe reports brought to him by 
unskilled persona, in an age before people had coDcemed themselves 
about the laws of evidence. It it jaat this historical enviranment 
that shows ns how great was tbe ordinarily sober judgment of Aristotl* 
and how unparalleled bis acumen in seeing the scientific significance of 
facts. It is, however, curioos U> note that Roger Baoon accepts the 
■tory as true : "quoniam si ipsa [mulier menstruata] aspieiat speoalum 
Dovuni, apparet nubes sangoinea in apeculo ex violentia i 
inficientis {Opti* Majtu, ed. Bridges, vol. L p. liS). 
AriMotU, p. 172. 


bodily orgaD. And so they naturally contain veins. 

10 When, therefore, the menstrual How takes place, owing to 
disturbance and flow of blood, there is a difference in the 
eyes, imperceptible to ua, but nevertheless real (for the 
seed and the monthly flow have the same nature), and 
the air is set in motion by the eyes, and the air being 
continuous to the mirror, it imparts to the latter a cer- 
tain quality and an impression similar to the one it has 
itself received, The air affects the surface of the mirror. 

1 1 But as the cleanest clothing is the most readily stained, 
so it is here. For a clean thing shows exactly whatever 
taint it receives, even the slightest effects, more tlian other 
things do. Bronze especially, owing to its smoothness, is 
affected by every contact (we must regard the contact of 
air as a kind of friction, as cleaning or washing), and 
owing to the purity of the bronze this contact, however 

12 slight, becomes visible. The reason why stains are not 
readily removable from new mirrors is to be found in the 
fact that they are clean and smooth. For stains pene- 
trate deep into such mirrors and in every direction; for 
owing to the mirror's pure surface the spots go deep and 
owing to its smooth polish they spread in all directions. 
In old mirrors the staiu does not fasten, for it does not 

13 penetrate so deep but stays rather on the surface. From 
these facts it is evident that movement is excited by 
slight distinctions, that sensation is swift, and further, 
that the sense -oi^au for colour not only receives 
impressions but also reacts on external objects. Facts 
regarding wine and the preparation of ointments also 

114 furnish proof for these statements. For the prepared 
oil and wine readily take up the smells of adjacent 



objects and they become tainted not merely with the 
smell of things thrown into them or mixed with them, 
but also of things that are placed or grow in their near 

In reference to our original inquiry let us lay down 460^ 
one fundamental truth, which is evidenced by what has 15 
been said, viz. that after the removal of the external 
sensible object, the experienced sensations persist. To 
this we must add that when under the influence of strong 
feeling we are easily deceived regarding our sensations, 
different persons in different ways, as e.g. the coward 
under the influence of fear and the lover under that of 
love have such illusions^ that the former owing to a 
trifling resemblance thinks he sees an enemy and the 
latter his beloved. And the more impressionable the 
person is, the less is the resemblance required. Similarly 16 
everybody is easily deceived when in anger or influenced by 
any strong desire, and the more subject one is to these 
feelings the more one is deceived. This is the reason why 
men sick of a fever^ sometimes think they see animals on 
the walls owing to some slight resemblance in the figures 
drawn there. And this tendency to illusion at times 17 
keeps pace with the intensity of the emotional experience, 
so that in cases where the patient is not very sick, he is 
stiU conscious of the deception, but where his condition is 
more aggravated, he . even rushes upon these animals. 
The explanation of this phenomenon is that the intellect 

^ AriBtotle here notes certain of the main canses of ordinary iUosioni 
and haUncinations, although the hallncination of fever-delirinin is here 
described rather as iUosion. The sense-stimulns is there in the picture 
on the wall, bat the inference is false. Cf. James, Principles of 
Psychology, vol. ii. p. 86. 



18 and the faculty in which our im^es ' arise do not pass 
judgment with the same power. A proof of this is that 
the sun appears to us only a foot in diameter and there 
is many another fact which contradicts our imagination. 
Also by crossing the fingers ^ a single object under them 
appears to be two and yet we do not say there are two; 

19 for sight is more decisive than touch. If, however, 
touch were our only sense, our judgment would declare 
that the single object is two. The source of illusion is 
found in the fact that things, whatever they may be, are 
perceived not merely while the stimulation of the sense- 
object continues, but also during the further activity of 
the sense itself, if this movement is the prolongation of 
that awakened by the sensible object. I mean, e.ff. the 
shore appears to sailors to move, although it is by some- 
thing other than the shore that the eye is set in motion. 


at inatfij^ of ra tpanTdaftaTa ytyreffffax 
Aristotle'n psjchology, does aot pais 
le,' io wbioh phantwnu rende, 

' Bead 1^ ™ ^rriafiaTi 
(4606 17). The imagiuati 
Judgment, klthoDgh the ' 
hu thii power. 

'Tbisia the oldest ex&mplc of f&raa I know, in the hiitorr 
of pajchulogj (cf. Jamea, Prindpla 0/ Pirj/chology, vol. ii. p. S6). 
The iJluatralion bu bacome claaaio&L In the nonn&l position o[ onr 
fingers (from which part of our taotusl world hu beeo bnilt ap), It i> 
imposuble to plue the radial aide of the index finger and the ulnkr aide 
of the middle finger on a marble or similar small object at the same 
time. Conseqaently when we crosa our fingers und perform this feat of 
touching tbe radial aide of the one and the nlnar side of the other with 
a marble, we seem to touch two objects, because these two poiuta 
OD our skin are never touched by a single abject at the same moment. 
Aristotle further refers to this inatance of illuaion in PrM. 9586 14, 
kod Sfelaph. 101la33. For a detailed discussioD of this and similar 
forms of illuaion, vid. Henri, t/lKr die Haumumhrnthmnnijen des 
TcMMHItM, pp. 67 ff. 


From these considerations it is clear that sense-processes, 
whether arising from external objects or bodily activities, 
take place not merely daring the waking state, but 
occur also in sleep, and that at this time they appear 
even more numerous. For during the day they are 2 
kept in the background by the combined activity of 
the senses and the intellect, and so are obscured, just 461 a 
as a small fire is obscured when placed alongside a larger 
one, or as trivial pleasures or pains are obscured alongside 
of great ones, but when the latter have vanished then 
the smaller ones rise to view. At night, owing to the 
inactivity of the special senses and their incapacity to 
function, caused by the return flow of heat from the 
outer into the inward parts,^ these sense-movements 
are carried to the primary seat of sensation and 
become clear, when the disturbance has subsided. And 
we must suppose, as tiny whirlpools occur in rivers,.^o 3 
each movement goes on continuously, frequently in the 
same direction, and again resolved into other forms 
through counter-influences. Consequently after eating, 4 

^Cf. Z>e«pmiio, 4676 20ff. 
Q 241 



and in the ease of very young persona, as e.g. in children, 
dreams do not occur. Tor there is a strong movement 

5 excited by the heat in food. The caae here is similar to 
what occurs in water when it is violently agitated, viz. 
sometimes no image is reflected and aoinetimes only an 
entirely distorted one,' so that the thing appears different 
from the reality. On the other hand when the water is 
still we see clear and distinct images. So, too, in sleep 
the images and residual movemen^ts resulting from 
sensations are sometimes entirely obliterated by a move- 
ment greater than the given one, and aometlmea visions 
appear confused and monstrous and the dreams are not 
marked by normal health, but are such as one finds in 
the atrabilious, in men sick of a fever, and in men that 
are drunken. For all these conditions are like flatulency, 

6 and excite great movement and disturbance. But when 
in sanguineous creatures the blood has come to rest and 
is separated off,^ the movement of sensation that proceeds 
from each sense-organ and persists, awakens normal 
dreams and causes an image to appear and the person to 


'Cf. note 1, p. 231. SenBationB cauie aftcr.moveiDeiits like the ripple* 
«ud circles in water agitated by n pebble. These movomenta repeat 
themaelvea io fainter form, clearly ia Btill wuter, and with distorted, 
broken shapes where the water is diBturbed by croaB-movementa. 
The circles or images are then confused or monstrous. If the movement 
it too violent, an after eating ajid in ehildreo, then, aa In riolantly 
Agitated water, no image or dream is prodnced. 

'That is, pari6cd from crass elements. Although Aristotle makes % 
distinction between pure and cross bloud, it is not certain that these 
are to he connected with the aorta and vena cava, or that they in any 
way correspond to arterial aoid venons blood. This sepuratiun take* 
place in the heart, which is at ODoe tha physiological and the psychical 
centre at animal life, — the "acropolis of the body" \Dt part, anitn. 


believe that he sees something owing to the influences 
discharged &om sight, and to hear owing to the influences 
discharged from hearing, and similarly with the other 7 
senses. For by the transmission of this movement from 
these special organs to the primary seat^ of sensation, 
one believes, in the waking state, that one sees and hears 461 ^ 
and perceives; and because it sometimes happens that 
sight seems to be stimulated without its being really so 
stimulated, we say that we see, and because touch reports 
two movements, we believe a single object to be twa In 8 
a word the primary sense affirms the deliverances of the 
special sense, when no other more decisive sense con- 
tradicts this. There is without doubt an appearance, 
but what appears is not in every case believed, unless 
the power of judgment is inhibited or is not exercised 
in its normal way. But as we said that some 9 
persons are subject to illusion under one condition and 
others under another, so when asleep, one is deceived 
by the processes of sleep, by the excitations of the 
sense-organs, and by other affections of sensation, 
to such a degree that something which bears only a 10 
slight resemblance to a given thing is thought to be 
that thing. For when one is asleep and the mass 
of blood recedes to the central organ, the movements 
in the blood, whether latent or actual, concentrate 
there.^ And the conditions here are such that if the 
blood is stirred, a particular movement rises to the 
surface and if this subsides, then another follows. They 
are related to each other like artificial frogs which rise to 
the surface of the water as soon as the salt on them is n 

> To the hmrt. * De aornno, 4666 23. Cf. note, p. 227. 

244 Aristotle's psychology dunbom. 

melted off. And so these movements are latent in the 
blood, and as soon as the hindrance is removed they 
come to active expression. When set free in the small 
amount of blood remaining in the sense-organs, they stir 
themselves, exhibiting a likeness to things such as we see 
in clouds, which resemble men and centaurs in quickly 

12 shifting forms. Each of these images is, as we have said, 
the residue of actual sensation. After the true sensation 
has gone, the image continues, and it is correct to say that 
it is something like Coriscus although not Coriscus. And 
at the moment of sensation the master-organ and judging 
faculty do not say that this is Coriscus, but only that 
owing to this sensation the real Coriscus is yonder 

13 person. On experiencing this sensation the master-sense 
makes the above deliverance, provided it is not entirely 
inhibited by the blood, just as without sensation this 
movement ia set up by the processes latent in the sense- 
organs. This latter, which resembles a thing, one then 
regards as the real thing. And the power of sleep is so 

14 great that it causes us to be unconscious of this difference. 
If one presses one's fingers under the eyes and does not 

462 a notice it, a single thing not only appears double but is 
believed to be so ; if the pressure is noticed the thing 
appears to be double but is not believed to be so, and 
this is what happens in sleep. If a person perceives 
that he is asleep and is aware of the sleeping condition 
in which the sensation occurs, then the appearance will 
be present indeed, but there is something in the person 
which says this is only a phantasm of Coriscus and is 
not Coriscus himself (for there is often something in the 
soul of the sleeper which says that the appearance is 


only a dream). If, however, he is not conscious of the 
sleeping state, then nothing contradicts the imagination. 

That the above statement is correct, and that we have 15 
movements of imagination in the sense-organs, becomes 
clear, if in falling asleep and on waking, we attentively 
try to remember what happens.^ For sometimes one 
will detect, on waking, that the images which appear in 
sleep are movements in the sense-organs. In the case 
of certain young persons whose sight is thoroughly good, 
there appear before them, when it is dark, a multitude of 
moving images, so that they conceal themselves in fright. 
From all these facts one must conclude that a dream is 16 
a kind of sleeping phantasm. For the imaginings in 
children just referred to are not dreams, nor is anything 
else which is seen when we have the free use of our 
senses. Neither is every imagination that occurs in 
sleep, a dream. For in the first place many persons 17 
have in sleep the power, in some form or other, of 
perceiving sound, colour,, flavour, or touch, although the 
sensation is weak and seems to come from afar. Persons 
who are asleep and open their eyes slightly, and then 
suddenly awake, have discovered the reality of the 
lamplight, which in sleep they saw only, as they thought, 
in a glimmer, and hearing the faint crowing of a cock, or 
the bark of a dog, they have, on waking, recognised them 
as loud voices. Some persons even reply to questions. 18 
For it is possible that when one or the other of these 
states, waking or sleeping, is unquestionably present, the 
other may be present to some extent. In these cases 

^One may see from this that Ariatotle was a oarefnl obseirer of 
the phenomena of conadonsness. 

246 Aristotle's psychology DBrasoM. 

there can be no dream, neither can such processes of real 
thought as occur in sleep, along with fancies, be called 

19 dreams.^ But a dream is that form of imagination that 
originates in the movement of sensation during the 
sleeping state as such. 

It has occurred in certain instances that men have 

20 never in their lives known themselves to have a dream ; 
462 b in other cases thej have observed them when far 

advanced in years without having noticed them earlier. 

21 The reason why dreams do not occur in these cases 
seems to be closely allied to the reason which prevents 
their occurrence in children, and after eating.^ For 
persons who are by nature so constituted that a large 
amount of vaporous-matter ascends to their upper parts, or 
the return of this matter produces in them great move- 
ment, it is reasonable to suppose that in these cases there 

22 are no dream-fancies. In advancing years there is nothing 
remarkable in the fact that dreams make their appear- 
ance. For where a certain ([physical]) change takes place, 
whether owing to age or to some internal affection, this 
changed condition ([regarding dreams]) must also occur. 

^The CMOS in which one diatingnishes an aotnal external atimnlna 
are not properly dreams. 

^The question whether or not there is dreamless sleep is not » 
settled one (cf. James, Principles of Psychology^ vol. i. p. 199 ff.). 
Hammond, Sleep and its Derangement, pp. 108 ff. The CSartesians, 
consistently with their definition of mind as a thinking entity, 
deny the possibility of a lapse of consciousness. Owing to its 
nature mind must always think. Kant says : " One can regard it at 
certain that there can be no sleep without dreaming, and whoever 
says he has never dreamed, has only forgotten his dream.*' Anlhro- 
pdogie, 4te AufL, Leip., 1833, p. 105. The disposition of modem 
psychologists is to regard dreamless sleep as probable, but the question 
is not Ukely to be removed from the region of dispute. Cf. Wundt, 
Human and Animal Psychology, Eng. Tr., p. 324. 



Regarding prophecy in sleep and the prophecy said to 
be derivable from dreams,^ it is difficult either to treat 
it with contempt or to believe in it For the universal 2 

^The attitude of Aristotle towards the widespread belief in the 
maotic character of dreams is marked by jadicial fairness. He finally 
concludes, however, that where dreams have been found to be pro- 
phetic, this is due merely to accident. Belief in them prevailed and to 
a certain extent continues to prevail amongst all nations, and is attested 
by all literatures from the earliest times (cf. lyior, Early History of 
Mankind f 3rd ed. p. 6 fif. ; Primitive Culture, 3rd ed. vol. L p. 121 ff.). 
"All argument is against it; but all belief is for it," as Tylor 
(vol. ii. p. 24) quotes from Dr. Johnson. This very accurately 
represents the state of Aristotle's mind toward the prophetic character 
of dreams. Greek literature especiaUy is full of references to mantio 
dreams, and the general soothsaying usages in Greek religion fostered 
belief in them. Oneiros (Dream) is sometimes called a god (II. ii. 6), 
again the messenger of Zeus, and Hesiod (Th. 212) tells us that 
dreams are the children of Night without a father, and the divine 
origin of dreams is witnessed to by Socrates {Orito, 44 a) and Xenophon 
{Anab. iii. 112). Aristotle belonged to the same intellectual era as 
Socrates and Xenophon. We find a similar belief in the prophetic 
nature of dreams witnessed to by the Hebrew Scriptures and the New 
TesUment (Oen, zzviii. 12, zL 5-21 ; Numbers zii. 6 ; MaUhtw L 20). 


248 Aristotle's psychology didivin. 

or widespread belief in the prophetic nature of dreams, 
based as it is on experience, lends support to this view, 
and it is not incredible that certain events are foreseen 
in dreams. There is a certain reasonableness in this, 
and so one might, in like manner, apply this belief to 

3 other dreams. The fact, however, that one cannot dis- 
cover any intelligible cause for their occurrence, creates 
distrust in them. The theory of divine origin is absurd, 
because in addition to its irrationality, one observes 
that these dreams do not come to the best and wisest, 

4 but to all sorts of men. But when their divine causa- 
tion is excluded, there is no other reasonable origin that 
one can assign. For it seems to transcend our power 
of understanding to discover an explanation of the story 
that certain persons foretell the future through legends 
on the pillars of Hercules or on the Borysthenes. Dreams, 

5 taken either in their entirety, or partially, or singly, 
must then be causes or signs of events, or else they 

6 must be accidental phenomena. ' Cause ' I understand 
in the sense of the moon's being the cause of the sun's 
eclipse,^ and fatigue being the cause of fever ; by ' sign ' 
I mean e,g, that a sign of an eclipse is a star's becoming 
visible in daylight or the roughness of the tongue in 
fever; by an 'accidental phenomenon' I mean e,g, that 
an eclipse of the sun happens while one is taking a 

463 a walk. For taking a walk is neither sign nor cause 
of an eclipse, neither is an eclipse the sign or cause 

7 of taking a walk. Consequently no accidental pheno- 

'Cf. Anal, post, 986 1, 99a 1 fif. Cause contains inherently the 
explanation of a result ; sign is merely a concomitant or a precursor, 
and has only an accidental relation to the reeolt. 


menon takes place constantlj or even as a rule. Is 
it, then, possible that some dreams are causes and others 
signs, e.g. of physical events? Well-educated physicians, 
at any rate, say that we should pay close attention to 
dreams. And this view is also regarded as reasonable 
by laymen who are investigators and philosophers. For 
the psychiccd movements that occur by day, unless they g 
are very full and vigorous, are unnoticed when they are 
experienced along with greater waking excitations. In 
sleep, however, the reverse is true. For then the 
trivial movements seem to be the important ones, as 9 
is apparent from frequently observed facts regarding 
sleep. When slight noises fall upon the ear one thinks 
it lightens and thunders, and when a bit of mucus 
flows into the mouth one thinks one is tasting the 
sweet flavour of honey, and when a very slight heat 
is felt in any member one thinks one is walking through 
fire and is fever-hot But when one awakes one dis- 10 
covers the real facta Since, then, all beginnings are 
small, it is evident that the beginning of disease and 
other bodily affections on the point of development will 
be small, and these necessarily show themselves more 
in sleep than in the waking state. Tet it is really 11 
not unreasonable to suppose that certain sleeping fancies 
are causes of actions peculiar to the individual For 
when we are on the point of doing something or are 
in the midst of it or have accomplished it, it frequently 
happens that we are occupied and busy with the same 
thing in a distinct dream (the explanation of which is 
that the dream movement has been already started 
from origins in the day's activity); and as this is true, 

250 Aristotle's psychology mdivik. 

so the converse must be true, viz. that the movements 
in sleep are often the starting points for the activities 
of the day, because the thought for the latter is already 

12 started on its way in our nocturnal fancies. In this 
sense, therefore, certain dreams may be signs and causes. 
But most prophetic dreams are things of chance, especi- 

463 ^ ally all those that transcend us and whose origination 
is not in our power, as e,g, a naval battle and remote 
events. The situation here is just like that of a man 
who thinks of a thing and in that instant the thing 
appears. For what is there to prevent this being also 
true of dreams ? It is even more likely that many 

13 accidents of this sort should occur here. Just as, in 
the former case, thinking of a thing is neither sign 
nor cause of the thing's appearing, so here the beholder's 
dream is neither sign nor cause of the event, but only 
accident. Consequently most dreams do not come true. 
For chance is that which occurs neither constantly nor 
even as a rule. 


Since other aDimals^ than man have dreams, one may 
say, in a word, that dreams are not sent from God and 
do not occur for his ends. They are, however, daemonic. 
For their nature is daemonic, but not divine. This is 2 
proven by the fact that very ordinary men have pro- 
phetic visions and true dreams, showing that God does 
not send them ; but such men as have a loquacious and 
atrabilious nature see all sorts of visions. And because 
these excitations are many and diversified they chance 
upon thoughts which correspond with reality, hitting 
the right thing here just as one sometimes hits in the 
game of " Odd and Even." * For in this instance the 
proverb applies : " Who often shoots will sometimes hit." 

^ " Quippe videbis equos fortis, cum membra iacebunt, 
In Bomnifl sudare tamen spirareque semper 
£t quasi de palma sumraas contendere viris, 
Aut quasi carceribus patefactis 
Venantumque canes in molli saepe quiete 
* lactant crura feamen subito vocisque repente 
Mittunt et crebro redducunt naribus auras." 

— Lucretius, Dt rtr, naU, iv. 987 ff. 

'Read Bekker*s conjecture dpTtdi;wT€s instead of Apna fXMpLiovrts, 


252 Aristotle's psychology dxdiviv. 

3 That many dreams do not come true is not strange. For 
even the signs in physical and heavenly pi^ocesses, such 
as the signs of rain and wind, often fail. For if another 
movement sets in which is stronger than the one indicated, 
the indicated event does not take place. Also many well- 

4 matured plans of what ought to be done fail of execution, 
because other more important motives arise. For not 
every expected event occurs, and one must not identify 
the future with the expected.^ Nevertheless one must 
say that there are certain causes to which this lack of 
fulfilment is due, and these are natural signs of the 

5 non-occurrence of the given events. 

In regard to dreams which are not due to such origins 
464<s as we have mentioned, but to origins that either in point 
of time, place, or magnitude are extraordinary, or which 
are not to be described in this way at all, and yet the 
dreamer does not have in himself the cause — in these 
cases, unless the prophetic character is accidental, it 
would be better to explain such foresight in the following 
way, rather than in the way employed by Democritus,* 

^ *Eff6fievov signifies the future absolutely and fUKKw the future con- 
tingently. Cf. De gen. et corr, 3376 6. 

^Democritus explains dreams by the same principles — images and 
effluxes — that he employs in the explanation of sensation. The images 
(efdwXa, simulacra) thrown ofif by things are complexes of atoms, which 
represent not merely the form, but also the inner qualities of things. 
They are the things in miniature, and are capable of conveying psychigal 
processes, as weU as physical features, from one person to another. 
Mind has an atomic composition, and it is owing to this fact that the 
opinions and feelings of friends are conveyed to us by their dream- 
images. Prior to Aristotle almost all philosophers, like Democritus, 
sought for an explanation of dreams outside the dreamer, dominated, as 
they were, in greater or less degree by contemporary superstition. Cf. 
Cicero, De divincU. i. 43 ; Plutarch, De plac, phU. v. 2, Quaest. con, 
viii. 10. 


who explains them by images and effluxes. Just as when 6 
water or air is stirred, the stirred part sets another part 
in motion, and after this has come to rest a similar 
motion is continued up to a certain point, even in the 
absence of the moving agent, so nothing prevents a 
certain movement and sensation from reaching the soul in 
sleep, produced by those objects from which Democritus 
says images and effluxes are thrown off. And these 
movements, reaching the soul in some way or other, are 
more distinctly felt at night, because they are more 
readily dissipated when they enter by day (for the night 
air is less apt to be disturbed owing to the calmer nature 
of night), and they awaken sensation in the body on 
account of sleep, for persons when asleep detect slight 
internal processes more sharply than when awake. These 7 
movements awaken fancies, out of which one foresees the 
future in events similar to the fancies. This power of 
prevision, then, occurs in any ordinary person, and not in 
the wisest. For if prevision were sent of God, it would 8 
come by day and to the wise. In this manner, however, 
it is reasonable that prevision comes to ordinary men. 
For the minds of such persons are not given to careful 
thought, but are, as it were, reft and empty of all content, 
and when stimulated they follow the lead of the moving 
agent. The reason why certain persons afflicted with 9 
ecstatic mania have prevision is that their own excitations 
do not distract them, but are rather thrown off by them, 
and, therefore, they have especial perception of processes 
foreign to them. That some persons have true dreams, 10 
and that familiar acquaintances have prevision especially 
regarding each other, comes from the fact that acquaint- 

254 Aristotle's psychology dbditim. 

ances concern themselves most about each other. For just 
as it is most true of intimate friends that they recognize 
and see each other at a distance better than others do, so 
it is also with these movements. For the movements of 

11 acquaintances are more easily recognized. The atrabilious, 
like long-distance throwers, owing to the vehemence of 
their natures, hit their aim. And owing to their mobile 

464 6 disposition they have a quick fancy for sequence. For as 
Phila^des^ in his poems and insane persons recite and 
think out sequences that depend on similarity, as illus- 

12 trated in the song of Aphrodite, so these dreamers string 
together a series of events. For owing to their passionate 
nature they are not swerved aside by extraneous move- 

The most skilful interpreter of dreams is he who 
can discern resemblancea For a plain dream can be 
interpreted by anybody. By resemblances I mean, 
as I said before, that the pictures of imagination 

13 are very like pictures in the water. In the latter, 
when the movement is violent, the reflection and 
picture bear no resemblance to the reality. And so a 
clever interpreter is one who can quickly distinguish 
and see at a glance in the confused and distorted 
picture the suggestion of a man, or horse, or whatever 

14 the given object may be. And as the picture in the 
water, so the dream can be similarly distorted, for 

^ Philaegides is an unknown poet. Leonioas (qaoted by Barth^lemy- 
St.-Hilaire, Comment, ad loc.) conjectures Philaenis, a Greek poetess 
of Leucas, contemporary of the sophist Polycrates, to whom an 
obscene poem on Love was ascribed. Michael of Ephesus {CommenL 
ad loc fol. 1527, p. 48) repeats the name Philaegides, as given in the 


movement destroys the distinctness of dreams. We 
have now explained the nature of sleep and dreams, 
and have given the cause of their occurrence, and have 
further explained the entire subject of divination by 
means of them. 




We^ must now inquire into the causes why some 
animals live long and others only a short time, and 
into the general subject of longevity and shortness of 

2 life. The initial point in our inquiry must be the 
stating of certain preliminary problems touching these 
phenomena. For it is not clear whether or not the 
cause of longevity and shortness of life is the same in 
animals and plants. Some plants are annuals, and 

3 others attain great age. Further, one may ask whether 
amongst the creatures of nature the long-lived and the 
naturally healthy are identical. Or is shortness of life 
to be kept distinct from questions of disease ? Or is it 
true that some diseases cause the body whose nature is 
affected, to be short lived, while other diseases in no wise 
prevent long life ? 

^ I have removed the brackets from the passage 4646 19-30, being 
unable to see any good reason for following Biehl in regarding it as 
an interpolation. 



Begarding sleeping and waking we have already 4 
spoken, and we must later on treat the subjects of 
life and death, and likewise disease and health, so far 
as they fall within the province of the philosophy of 
nature. At present we have to consider, as already ^6$ a 
said,^ the causes of longevity and shortness of life. This 
distinction of longevity marks entire genera in comparison 
with others, and again it marks certain members of one 
species in comparison with other members. By this I 5 
mean there is a generic difference in longevity applicable 
e,g. to man and horse (for the genus man is longer lived 
than the genus horse), and again within the species one 
man is longer lived than anotl||r. For some men are 
long lived and others short lived, according to the 
districts they inhabit. Nations that inhabit warm 
countries live longer ; the inhabitants of cold countries ' 6 
are less long lived. And amongst those that inhabit the 
the same locality there are also between individuals 
differences in this respect 

' Retain the reading KaddTep, ir.r.X. (465a 2) bracketed by Biehl. 

*Thi8 statement is not borne out by statistics, at least onder 
present conditions. Nevertheless the statement may have been 
correct in Aristotle's time. Inasmach as the North Countries were 
then inhabited by people of inferior civilization, it is likely that 
the period of life was less than it is now under conditions of higher 
civilization. The more civilized races protect the aged, and so 
contribute to longevity, besides being generally better equipped with 
means and methods for self-preservation. Cf. Lankester, ComparcUive 
Longevity, p. 107 ff. ; Van Oven, Decline of Life m HeaUh and JDiaeeue, 
pp. 60, 61. 



We must understand what is easily destroyed in natural 
structures and what is destroyed with difficulty. Fire 
and water and other ^ements akin to them, without 
having their power, axe, in their reciprocal action, the 
causes of generation and decay. Consequently, everything 
else, one may reasonably suppose, that is derived from or 
composed of these elements, shares in their nature, except- 
ing such things as are artificially composed of a great 

2 many parts, like a house. The discussion of these other 
elements does not belong here. Many things are subject 
to destruction from causes peculiar to themselves, as e.g. 
knowledge, health, and disease. For these are destroyed 
when the things of which they are qualities are not 
destroyed but survive, e,g. the agency which destroys 
ignorance is recollection and learning ; the agency which 
destroys knowledge is forgetfulness and error. Acci- 

3 dentally, the destruction of other properties goes hand 
in hand with the destruction of the natural body. For 
when animals are destroyed the knowledge and health 

4 that are in them are also destroyed. From this one 
might draw a conclusion regarding the soul. For if 



the soul is not in the body by natural growth, but is 
there just as knowledge is in the soul, then it would be 
exposed to another destroying agency in addition to that 
to which it is liable in the destruction of the body. 
But this does not appear to be the case; the relation 
between soul and body must be differently understood. 


465^ Perhaps one might reasonably ask the question: la 
there any place where the perishable is imperishable, as 
in the case of fire in the Empyrean, which is subject 
to no opposing influence; for the properties that attach 
to opposites are incidentally destroyed by the destruc- 
tion of the thing itself. For opposites destroy one 
another. No opposite, however, which belongs to sub- 
stance is incidentally destroyed, for substance is not 

2 predicated of any subject. Consequently, in whatsoever 
thing there is no principle of opposition, and where there 
is no such principle, there can be no destruction. For 
what is there to work destruction, if destruction is 
effected exclusively by opposites ? But there is no op- 
position present, either absolutely or in any particular 
part. Or is this true in one sense and in another false ? 
For whatever has matter cannot avoid being in some 

3 sense subject to opposition. It can be everywhere hot 
or straight, but it cannot be in its entirety hot or 
straight or white. For these qualities would then be 
separate entities. Whenever the active and passive 
come together, if the one always acts and the other 

4 is always acted upon, change must take placa Further,. 



I if change necessarily produces a residue, Iben residue 

I involves opposition. For change is always the result 

of opposition, and residue is that which remains irom a 

state prior to change. But if tlie actually opposed were 

entirely excluded, a thing would, in this case, be im- 

- perishahle.' Or is this untrue, but a thing in this event 

I would be destroyed by its environment? If this happens, s 

L then the above explanation is adequate.' If the destruc- 

Ltion is not so produced, one must suppose there is an 

I actual inherent opposition in the thing, and that a 

residue is produced. For this reason the lesser flame 

is incidentally consumed by the larger one, because the 

food which the smaller one consumes in a long time 

in the form of smoke, is consumed by the lai^er one 

qnickly. And so everything is in constant motion^ 

constantly coming into existence and passing out of 

existence. And the environment either assists or opposes. 6 

Constantly changing things may last a longer or a 

^shorter time than their own nature prescribes, but 

I nothing lasts for ever, where opposites exist. For at 

I the very start, matter contains in itself the principles 

I of opposition, so that if one employs the category of 

I piece, spatial change is involved ; if one employs the 

I category of quantity, we have changes of growth and 

l-decay ; if one employs passivity, then qualitative change.* 

■ That IB, if thaprineipleof oppoiitinn trere aiclnded there wonldbeno 
1 «huige, uid if tliere were no cbBnge, a thing wnuld be indestractible. 
le environiiieiit, in that case, vonid supply the principle of 
oppodtioD, Bnd lo the dogma of "no opposition, no deBtniDtioa" 
would remain unchallenged. 

'In other words, the whole of the terrestrial world is sabjeol tc 
eorruptibility and ch«nge (ifttaph. 1036a 2S, 1W96 2i; Dt coeto 


466 a Neither are the largest creatures less exposed to de- 
struction than others (for the horse is shorter lived than 
man), nor the smaU animals (for many insects Uve only 
a year), nor, in general, are plants longer lived than 
animals (for some plants are annuals), nor are sanguineous 
animals, by virtue of their being sanguineous, long lived 
(for bees live longer than do certain sanguineous 
animals), neither are the bloodless animals, as such, 
long lived (for molluscs, which are bloodless, live only a 
year), nor land animals (for there are both plants and 
land animals that live only a year), nor sea animals (for 
2 the crustaceans and molluscs are short lived). On the 
whole, the longest lived organisms are found amongst 
plants, an example of which is the palm.^ Next the 
sanguineous live longer than the bloodless animals, and 
the land animals longer than those that live in water.' 

^ Apart from the mge attained by man, and by certain inaecta and 
plants, little Ib accurately known about the longevity of organiims 
(Lankester, op, eit, p. 12). 

* Dr. Gunther (quoted by Lankester, op. eit. p. 13) says : " There is 
scarcely anything positive known of the age and causes of death of 
various fishes," but oases are reported of carp attaining the age of 150 



So that the longest lived animals are those where we 
find the combined marks of having blood and living on 
the land, as instanced in man and the elephant^ It is a $ 
rule also that the larger animals are longer lived than 
the smaller one& And this characteristic of size applies 
to other examples of longest lived animals, as well as 
to the instances cited. 

yean, and pike 267 yean (I) and elephants are reported to have lived as 
long as 500 years {ib. p. 59), bat the statements are not properly 
aathentioated. Trees are reported to have attained ages ranging from 
335 years (Elm) to 3200 years (Yew), and even to above 4000 yean 
(Taxodiam). In the Popular Science Monthly (voL ii. p. 250) the story 
is told of a carp killed at Chantilly aged 475 years. Weismann says 
that large trees have the longest life of all organisms in the world, and 
the "largest animals also attain the greatest age . . . and it would not 
be difficult to construct a descending series of animals, in which the 
duration of life diminishes in almost exact proportion to the decrease 
in the size of the body." Essays upon Heredity , Eng. Tr., p. 6. A 
general rule such as this would, of course, have many exceptions, as e,g. 
in the case of the eagle and horse, the former being inferior in sice but 
superior in longevity. 

^ Aristotle reports the age of an elephant at 200 yean, or, according 
to another report, at 120 yean, for his statement is made only on 
hearsay (ol fUw ^o^-c. Hist, anitn. 6306 23). 


The cause of all this might be discovered in the following 
facts. One must understand that an animal is by 
nature moist and warm, and life is also moist and 
warm, whereas old age is dry and cold, and so is death. 
And this is plain to observation. The matter in living 
bodies has these qualities of weirm and cold, dry and 

2 moist. As beings grow old they must then dry up, and 
so the moist should be constituted in such way as not to 
dry up easily. Now, fatty elements do not readily 
decay. The reason is that they contain air, and air 
compared with other elements is fira But fire is not 
subject to decay. The amount of moisture should not 
be small, for a small amount is quickly dried out. 

3 Consequently, larger animals and plants are, as a rule, 
longer lived than others, as we said before. For it is 
reasonable to suppose that the larger creatures possess a 
greater supply of moisture. But it is not merely for 
this reason that they are longer lived, for there are two 
causes of long life, a quantitative and qualitative cause- 
Consequently, there must not merely be a certain quantity 
of moisture present, but this must also be warm, in order 



that it be not easily congealed or dried up. It is for 4 
this reason that man is longer lived than certain larger 
animals. For animals that are defective in the mass of 
moisture are longer lived, provided their excess in the 466^ 
quality of this moisture is relatively greater than their 
defect in its quantity. Some animals have an oily 
warmth, in consequence of which their moisture is not 
easily dried up or chilled. Others again have a moisture of 
a different sort. Further, whatever is meant to be difficult 5 
to destroy should not throw off much residue. For this, 
whether it be due to disease or to nature, destroys a 
thing. Besidue has the significance of opposition and is 
destructive of a thing either in its entire nature or in 
some part of it Consequently, salacious animals and 
such as abound in seed age quickly. For seed is a 
residue and when it is thrown off produces dryness. For 6 
this reason a mule lives longer than a horse or an ass, 
and women live longer than men, in cases where men are 
lascivious. And so male sparrows are shorter lived than 
females. Further, males subjected to hard labour are 
short lived, and on account of toil age more rapidly.^ 
For toil produces dryness, and old age is dry. In the 7 
ordinary course of nature, and taking it all in all, men 
live longer than women.' The reason for this is that 
the male is a warmer animal than the female. The same 

' Excessive expenditare in organic metabolism dae to labour, yiolent 
activity, inordinate eating, etc., on the one band, and waste in pro- 
pagation on the other, reduce the tenare of life. 

'Statistics show that females have a longer average of life than 
males (Lankester, op, cU, p. 117). A writer in the Satwrday Review 
(vd. 79, p. 24S) shows that in polygamous races, the males are shorter 
lived than the females. 

266 Aristotle's psychology del.btb.vit. 

classes of animals live longer in a warm than in a cold 
climate, for the same reason that the larger animals 

8 live longer than smaller ones. Particularly striking in 
this connection is the size of the naturally cold animals. 
So snakes, lizards, and rough-scaled reptiles found in 
warm localities and the testacea of the Bed Sea attain a 
great size. For warm moisture is the cause of growth 

9 and life. In cold districts animal moisture is more 
watery and consequently easily congealed, so that 
animals with little or no blood, whether their habitation 
is the land or water, do not occur at all in the northern 
regions, or if they occur they are smaller and shorter 

ID lived. For frost impedes growth. Both plants and 
animals perish when they get no nourishment, for then 
they consume themselves. Just as a larger con- 
sumes and destroys a smaller flame by using up its 
food, so the natural warmth, whose primary function is 
digestion, consumes the matter in which it is found. 

II Aquatic animals are shorter lived than land animals, not 
because they are moist unqualifiedly, but because they 
467 a are watery. Moisture of this sort is very perishable, 
because it is cold and easily congealed. For the same 
reason the bloodless animal is very perishable, unless it 
is protected by great size, because it contains no oily or 
sweet element. I say sweet, for animal fat is sweet 
Consequently bees are longer lived than other animals 
that are larger. 


It is amongst plants that we find the longest lived 
organisms, and these attain a higher age than animals, in 
the first place because they are less watery and therefore 
not easily congealed. Secondly, they contain a viscous 
oily substance, and therefore, although they are dry and 
earthy, they nevertheless possess a moisture which is not 
easily dried out. We must now find an explanation for 2 
the great age attained by trees. For a peculiar explan- 
ation applies to them which does not apply to animals, 
excepting insects. This peculiarity is that plants con- 
stantly renew themselves and so attain great age. For 
new shoots are put forth from time to time and others 
grow old. And the same thing is true of the roots. 
But this renewal does not take place in all parts at 3 
once; sometimes only the trunk and branches die and 
others grow up alongside of them. And when this 
happens other roots spring from the remaining part. And 
so it continues, one part passing out of existence and 
another part coming into being. Consequently, they live 4 
long. Plants have a resemblance to insects, as already 

said. For life continues when they are divided, and out 


268 Aristotle's psychology dbl.stb.yit. 

of one insect or plant two or several are produced. 
Divided insects, however, reach merely to the state of 
living, but are not able to continue long in life. For 
they have no organs, and the principle of life in the 
single part has no power to develop an organ. This 
principle in the plant, on the contrary, has the power of 
developing organs, for it contains in every case both root 

5 and stem potentially. Consequently, the new and the 
ageing branch keep growing from this, differing little in 
their length of life, just as it is with grafts. In the 
grafting of shoots, one would say that in a certain sense 
this same process occurs, for the shoot is part of a 
plant. In the grafting of shoots, however, the conti- 
nuity of life occurs in a state of separation from the 
mother plant, while in the other cases the lives are 

6 conjoined. The reason is that the inherent potential 
principle in the plant is all-pervasiva 

There is, however, a point of identity between animals 
and plants. In animals the males are, as a rule, longer 
lived than the females. For their upper parts are larger 
than the lower ones (the male is more dwarflike ^ than 
the female) ; the warm element is found in the upper 

7 parts and cold in the lower ones. Also plants with 
467 d large roots are longer lived than the others. Annuals 

are not of this kind, but trees ara For the upper part 
and head of a plant is the root, but annuals have their 
main growth towards the lower' parts and the fruit. 

8 These questions will be examined in detail in the treatise 

^ That is they have larger heads and shoalders. 

* Vis. towards the branches, which are analogoos to the lower parts 
of man. 


On Plants} For the present we have explained the 
cause of longevity and shortness of life in animals. 
There remain for our consideration the subjects of 
Touth and Old Age, Life and Death. And after these 
have been investigated, our treatise on animals ' will 
have been finished. 

^ The two books of Aristotle {HiU. an, 539a 20, Dt gen. an, 716a 1), 
Ttpl ^vTup, appear to have been stiU in existence at the time of 
Hermippns, but to have beon finally supplanted by the completer work 
of Theophrastus on the same subject. Ct, Zeller, PhUonophit d, Oriech. 
Th. II. Abth. ii. 3te. Anfl. p. 9S. 

' Owing to this statement Brandis [Handbuch d, Oegchichte d. PhUo8. 
p. 1192, 93) thinks that only the first five tractates of the Parva 
naturcUia were written immediately after the De anima, while the 
three following (viz. On Longevity and Shortness of Hfe^ On Touth 
and Old Age, and On Respiration) were written after the completion of 
the treatises on Zoology. There is no reason why this should not be 
true, althoagh proofs from cross-references in Aristotle's writings are 
never very cogent for their chronology, such references being often a 
later addition. It frequently happens that the treatise X cites the 
treatise Y, and the treatise Y cites the treatise X, such additions and 
references (particularly when at the beginning or end of a work) being 
added often by an editorial hand. The Topics, e,g. quotes the 
Analytics {Top. 162a 11, 1656 8), and is quoted by the Analytics {An. 
prot. 246 12, 64a 37, 656 16). 




We must now treat of youth and old age, and of life and 
death. At the same time it may be necessary to explain 
the causes and conditions of respiration. For in some 
animals^ life and death are conditioned by respiration. 

2 We have elsewhere treated more precisely of the soul, 
and it is clear that its ultimate nature cannot be corporeal, 
although it has its seat evidently in some part of the 
body, and in some part, too, that has a higher importance 
amongst the body's members.^ For the present we must 

3 dismiss the other parts or powers of the soul (whatever 
may be the proper term to apply* to them). In regard to 

^ Only animals endowed with lungs or analogous organ may be said 
to respire. The employment of water by fishes serves a similar purpose 
(refrigeration or regulation of temperature), but is not respiration. In 
such animals as respire, life and death are conditioned by the perform- 
ance of this function. 

' In the heart. 

>Cf. De an, 414a 30 £, 4336 1, 416a 26, 416a 20. 



creatures that are termed animals and have life, in cases 
where they are endowed with both attributes — I mean 
with animality and life — ^it must be that the principle 
whereby they live, and by virtue of which they are called 
animal, should be one and the same part^ For it is 4 
impossible for an animal as animal not to have life. 
On the other hand, it is not necessary for a thing to be 
an animal because it has life. For plants live, and yet 
they have no sensation, and it is in terms of sensation 
that we distinguish the animal from the non-animaL 
Numerically they are one and the same part, although in 
their mode of expression they are manifold and different' 
For it is not the same thing to be an animal and to have 
lifa Since amongst our sense-organs there is one which 5 
we call a kind of 'common sense,' where all our actual 
sensations must come together, this * common sense ' must 
occupy a position midway between what we call the anterior 
and posterior parts of the body (by anterior* is meant that 
which is situated towards the region of sensation, and by 
posterior that which is situated in the opposite r^on). 
Furthermore, since in all living organisms the body is 
divided into an upper and lower half (for all animals as 
well as plants have an upper and lower part), the nutri- 
tive principle should evidently^ occupy a position midway 468 « 

^ /.e. nutrition and sensation are functions of one life-principle. 

' The fundamental mark of a living thing is the power of nutrition and 
propagation ; the fundamental mark of an animal is sensation. Both of 
these functions in the animal are performed by the central organ. 

'By anterior is meant upper, t.e. towards the region of the senses, 
which are mainly about the head. 

^Aristotle assumes this, of course, owing to his teleological view of 
nature. Nature operates in the way that is best. 

272 Aristotle's psychology DsjmmiT. 

between them. The part which contains the organ for 
admitting food is called the upper part, and we use the 
term ' upper ' here in reference to the body itself and not 
in reference to the directions of the surrounding universe;^ 
by ' lower ' we mean the part whose primary function is 

6 to void excrement. In this connection we find a wide 
difference between plants and animals. In man more 
than in any of the other animals, owing to his erect 
attitude, we find the upper part turned towards the upper 
part of the universe; in the other animals^ the upper 
part is turned in a direction midway between the upper 
and lower parts of the universe ; in plants, which are 
fixed on one spot and draw their nourishment from the 
earth, this upper part must in every case have a down- 

7 ward direction. For roots in plants and mouths in 
animals are analogous organs, by means of which in 
the one case food is derived from the earth, and in 
the case of animals through themselves.* 

^ Upper in reference to the aniverse signifies the direction in which 
flame and light substances move (cf. Phya, 2006 19, Meiaph. 10656 13). 

* Cf . Sallnst, De conjur, CcU, i. 

* Animal food in its final form is, in Aristotle's theory, the blood. 
Cf. De somno, 456a 34 ; DejuverU, 469a 1, 32 ; De part. an. 678a 6. 


All perfectly developed animals are analysable into 
three parts — one for the admission of food, a second for 
the voiding of excrement, and a third midway between 
these two. The last of these is called in larger animals 
the chest, and in the smaller some equivalent term 
is used ; ^ in some animals, however, it is more clearly 
articulated than in others. Again, such animals as are 2 
capable of progressive motion have, in addition to the 
parts mentioned, other organs adapted to the service of 
movement and to carrying the entire trunk — as 1^, 
feet, and other organs that have the same function as 
these. The nutritive principle of the soul is situated in 3 
a region central to these three parts, as is evident both 
from observation^ and reason. In fact there are many 
animals which, after one or the other part has been 
cut off, even the head and the organ for seizing food, 

^The general thoracic region. 

* That IB, on empirical and a priori grounds. If this central ntoa- 
tion \b the best for the performance of functions in which the entire 
body is interested, then it is reasonable to suppose, Aristotle says, that 
nature has placed the nutritive principle here. 
8 273 



continue to live io that port to which the middle is 

4 conjoined. This fact may be plainly observed in the 
case of insects, such as wasps and bees. Also many 
animals besides insects, when cut in two, can continue 
to live by the functioning of the nutritive principle. 
This nutritive part is actually unitary, but potentially 
multiple, and the natural construction of these animals 
is the same as that of plants. For plants after they are 
divided continue to live in segments, and from a sii^le 

5 origin one can by section produce several ' trees. Why it 
is that some plants cannot continue life after section, while 
others can be propagated, must be explained elsewhere. 

4684 In this respect, however, plants and insects as a class are 
alike. It is necessary that the nutritive principle in 
those living things that possess it' should be actually 

6 one, though potentially multiple. And the same holds 
good of the principle of sensation ; for the segments 
evidently have sensation. In reference to the main- 
tenance of their natural life, plants ([when divided]) are 
able to survive. Animals are not, for they lack oi^ans 
for their preservation, wanting in some instances organs 
for the seizure of food, and in others for receiving it into 
the body, and in other instances wanting other organs in 

7 addition to both of these. Such divisible animals 

' In the lovrer fonuB of aDioud life, ks in vegetAble ltf«, organic 
fanutioas are leta centralized than in higher orders. In all of them, 
however, there ii a certain amount of oeotratizBtion, and even in inaecta 
life continues only a short time in any member after severance from the 
middle segment Cf. above, 467a 20 ; HUl. an. 531b 30 fl*. ; 
Be an. tUb 23. 

°Ogle, in his translation of this tractate (London, 1897, p. lOS) 
mggeata for ^auoii', ^irifuii. Cf. , howersr, 479a 8, where we have the 


resemble a complex of several creatures grown together. 
In the most perfectly organized bodies, however, this 
phenomenon is not found, because their natures have been 
fashioned into the greatest possible unity. There are 
always, however, certain dissected members which exhibit 
slight sensation, because they are still under the influence 
of a certain psychical^ affection. For after the entrails 
have been removed, bodily movements are still continued, 
as one observes in tortoises after the removal of the 

^ Aristotle knew nothiiig of the nature of reflez-movementa, having 
no knowledge of the nervous system and regarding the heart and not 
the brain as the centre of psychical life. James {PrincipUa, 
vol. L p. 16) cites the case of Robin, who, on tickling the breast 
of a criminal an hour after decapitation, saw the arm and hand 
move towards the irritated point. Ogle {op, cU, p. 109) says that 
''insects, sach as grasshoppers, from which the viscera have been 
entirely removed and replaced by cotton-wool as entomological 
specimens, if not pinned down, often fly away." 


Wb have further proof of the central situation of the 
nutritive principle in the case of both plants and animals. 
In the case of plants we observe their generation from 
seeds, and we also note the phenomena of grafts and 

2 slips. Generation from seeds takes place in every 
instance from the centre. All seeds are bivalvular, and 
the point at which their two halves are joined is the 
point from which generation begins and the middle in 
reference to the two parts. It is from this point that 
stem and root shoot forth in growing plants, and the 

3 point of origin is also the central ^ point. This pheno- 
menon may be observed in the case of the buds of 
grafts and slips, for the bud is in a sense the life-principle 
of the branch and at the same time its centra It is the 
bud, therefore, which one removes or into which one 
inserts a graft, in order to produce branch or root from 
it, on the theory that the origin of life in branch or root 

^ Similarly Aristotle regards the heart or animal centre as the part in 
which life originates, and notices that it is visible in very small aborted 
embryos, and is observable in the egg on the third day {De pari, on. 
6656 1). 



is the centre. In sanguineous animals the first organ in 4 
development is the heart. This is plainly seen in 
those animals whose process of generation admits of 
observation. In bloodless animals the organ that 
is analogous to the heart must be the first de- 
veloped. We have already said in our earlier treatise, 5 
On the Parts of Animals^ that the heart is the organ 
from which the veins proceed, and that the blood in 
sanguineous animals is the ultimate source of nourish- 469 <> 
ment, out of which the members are generated.^ 
Although regarding nourishment it is plainly the office 6 
of the mouth to perform one certain task, and the 
office of the stomach to perform another task, yet the 
heart is the master-organ and sets the end for all 
the others. Consequently, in sanguineous animals it is 7 
in the heart that we must look for the origin of 
nutrition and sensation. For regarding the preparation 
of food, the functions of the other organs are subordinate 
to the function of the heart. It must be true that 
the master-organ is that which works persistently 
towards the end and does not stop with that which is 
subordinate to the end, just as a physician persistently 
works towards health. At any rate, the dominating 8 
organ of sensation in all sanguineous animals is found 
in the heart, for the 'common sense' which serves all 
the special senses must be situated thera There are 
two senses, taste ^ and touch, whose channels lead mani- 

^ De part, an, 605a 15. 

^De 9omno 456a 34. Cf. also thia tractate 469a 2S ft; Dt rt$p, 
481a 11 ; Dt part, an, 678a 7 ; De gen, an, 740a 21. 

' Taste, as has been already said, is a sort of touch, and both taste and 
touch are connected with the heart by means of channels (xdpoc), by 


feetly to the heart, and what is true of these must be 
trae of the other sense& Movement in the other sense- 
organs may be transmitted to the heart, but with the 
upper parts of the body these two senses ([touch and taste]) 

9 do not communicate at alL Apart from these con- 
siderations, if the life-principle in aU animals is situated 
in the heart, the sensory principle must evidently be 
found there also. For that by virtue of which we call 
a thing an animal is the same as that by virtue of 
which we say that it lives, and the differential mark 
of sensation is the same as the differential mark of a 

lo living body. The reason why certain senses are, as we 
see, connected with the heart and others with the head 
(in consequence of which some philosophers^ r^ard 
the brain as the organ of animal sensation), has been 
given in a separate treatise.' 

which Aristotle probably underatood the veins diffoeed throagh the 
flesh and leading to the central organ (De pari. an. 656a 29). Their 
medium is elsewhere described as the flesh itself {De gen. an, 744a 1). 

^ Plato and Diogenes of ApoUonia. 

>De part, an, 686a 5 ff. 


From what we have said, based on observed facts, it is 
dear that the principle of sensation, as well as that of 
growth and nutrition, is situated in this organ ([the heart]) 
and in the middle of the three divisions of the body. On^ 
the basis of deduction we should say the same thing, 
because we see that nature, out of existing possibilities, 
does in every instance the best Now, if each 
principle^ is situated in the central section, the parts' 
(viz. that which finally elaborates the food and that 
which receives it) would thus perform in the best 
possible way their several functions. For to each of the 
parts the central organ will then be so related as is best, 
and the mid-position in a case such as this is the position 

^ The editions of Bekker begin Chap. iv. here. 

' Namely, the prindples of sensation and nntiition. 

' Aristotle's meaning appears to be that if the nntritive principle as 
weU as the principle of sensation is lodged in the middle section, then 
the two parts of nutrition, viz. elaboration of food and its assimilation, 
woald be best performed. In other words, the heart, as the organ of 
natrition, would in this way be best placed for preparing food for 
distribution to the surrounding parts, and the surrounding parts, as 
receivers {t6 ^ffrtic6v), would be best served by a centrally situated souroe 
of supply. 


280 Aristotle's psychology dejuvewt. 

4^^ that naturally belongs to a ruling principle. Again, one 

2 must make a distinction between the user and the instru- 
ment used (and as they differ in function, so too, if possible, 
they should differ in position), as a flute and the hand 
that plays it are different in function and situation. If, 
then, to be an animal means to have the power of 
sensation, this power in the case of sanguineous animals 
must be found in the heart and in bloodless animals in 

3 a corresponding organ. Every member and the entire 
animal body possess to a certain degree congenital 
heat. Consequently we see that during life animals are 
warm, but when dead and deprived of life they are cold. 

4 The source of this heat in sanguineous animals must be 
sought in the heart, and in bloodless animals in the 
analogous organ. For all the organs (especially the 
dominating one) prepare and digest their food by means 

5 of natural heat. Consequently, all the other parts of the 
body may become cold and yet life may continue, but when 
the master-organ becomes cold, life is destroyed entirely, 
because this is the source of heat for distribution to all 
other organs, and the soul is as it were suffused with fire 
in this organ, which in sanguineous animals is the heart, 
and in bloodless animals an organ analogous to the heart. 

6 Life, then, must go hand in hand with the continuance of 
this heat, and what we call death is its discontinuance. 


There are two ways in which, as we see, fire may be 
extinguished, viz. it may either go out or be put out. 
In the former case we say the extinction is caused from 
within, in the other case it is caused by opposing forces ;^ 
an example of the former is old age; of the latter, 
external violence. Extinction in both cases, however, is 
due to the same ultimate cause, viz. the failure of fuel, 
for when fuel fails and the heart can no longer receive 
sustenance, extinction of the fire ensues. Cold, by 2 
retarding digestion,' arrests nourishment. And there 
are times when it extinguishes itself, as, e.g.^ when the 
heat is massed in too great quantity,^ owing to lack of 

^In either case the eztinotion is due to the mscendency of cold over 
its contrary heat. Only in the former case, according to Aristotle, the 
extinction is due to the normal failure of fuel through exhaastion ; in 
the latter case the extinction is due to unnatural or artificial exposure 
to cold or wet (which Aristotle calls opposing forces), thus abnormaUy 
checking the production of heat by the blood, and violently bringing 
the supply to an end. 

'Digestion (r^ci) means ' cooking.' 

'Excessive heat is here conceived of as too rapidly exhausting the 
supply of fuel, as in the case of fever or in old age (owing to its 
diminished supply of fuel). In addition to this the lungs in old age 


282 AMSTOTLB's PSYCHOLOGY dejuvwit. 

respiration or lack of cooling. And when the heat 
accumulates in such mass, it soon causes an exhaustion of 
fuel, and this process of exhaustion takes place before 

3 evaporation has time to develop. Not only, then, is a 
smaller fire extinguished by a laiger one, but also the 
flame of a lamp is consumed within itself when immersed 

470a in a large flame, just as any other combustible would be 
consumed. The reason for this is that the larger flame 
uses the fuel contained in the smaller before other fuel 
can take its place, and the fire continues in constant 
process of development and in constant flow like a river, 

4 but we do not observe this on account of its rapidity. It 
is clear, then, that if the heat is to continue (and this is 
necessary if life is to continue), there must be some 

5 means of reducing the heat in the chief organ. An 
illustration of this may be had in what takes place in 
quenched coals. For if coals are kept closely covered in 
a common oven, the fire is quickly extinguished. 
Whereas if one in rapid alternation removes a lid and 

6 sets it on again, the coals continue lighted a long time. 
Covering a fire with ashes also keeps it. For owing to 
the porosity of the ashes ventilation is not prevented, 
and the ashes, by admitting the surrounding air, protect 
the fire against extinction through excess of heat arising in 

7 it.^ However, the explanation of the fact that opposite 

become dry and hard, and do not so weU perform their function of 
regulating the temperature. Of. De reapir. 47S6 35, 479a 7 ; MeUor. 
379a 6 ; De gen, an. 7836 7. 

1 In other words, the surrounding air being admitted by the porous 
ashes prevents the excessive heat within from exhausting its fueL 
Analogous to this is the reduction of the vital heat by the ventilation of 
the lungs. 


effects are produced by covering a fire with ashes and with 
an oven-lid (for the latter extinguishes it and the former 
keeps it a long time) has been given in our treatise 
On Problems} 

^ The qnestion is not diaoiuBed in the extant ProbUma, 


Since every living thing has a soul, and the soul, as we 
have said, cannot subsist without natural heat, we find 
that in plants adequate provision has been made for the 
preservation of natural heat through nutriment and the 

2 surrounding air. For food produces refrigeration in 
organisms when it is first introduced, just as on its 
entrance it does in man. Whereas fasting creates heat 
and produces thirst. For air, when it is stagnant, always 
becomes heated, but when set in motion through the 
admission of food it is cooled, until the food has under- 

3 gone digestion. On the other hand, if the surrounding 
air is excessively cold, owing to the season and the occur- 
rence of heavy frosts, plants are dried up, or if intense 
heat occurs in summer and the moisture derived from the 
soil is inadequate for refrigeration, the natural heat is 
extinguished and destroyed. In such seasons one says 

4 that trees are frosted or suffer blight. And that is the 
reason why people pile certain kinds of stones ^ about the 

^ Whether any partioolar variety of stone was used for this pnrpose is, 
so far as I am aware, unknown. Presumably nothing more is meant 
than that such stones were used as lent themselves to making a compact 



roots or cover them with vessels of water, in order to 470^ 
keep the roots of the plants cooL In the case of 
animals, since some of them are aquatic and others live 
in a medium of air, the refrigeration is derived from and 
through the media in which they live, i.e, in the one case 
water and in the other air. We must now begin a 
special inquiry touching the nature and manner of this 

oovering, thos shattiiig oot the heat, or snch stones as by their density 
were poor oondnctors of heat. In any case the chief idea is that they 
performed the same service ss lungs and gills in animals, viz. the 
service of refrigeration or the prevention of excessive heat, as Aristotle 



A FEW of the earlier physicists ^ have treated the subject 
of respiration. But in regard to the purpose which it 
subserves in the animal organism, some of them have 
given no explanation whatever, and others, although they 
have discussed it, have been wrong in their statements and 
have lacked empirical knowledge of the facts. Further- 
more, they declare that all animals respire.^ This, however, 

^ Diogenes of ApoUonia, who explained thought aa weU aa life by 
means of respiration (Zeller, Phil, der Griechen, 4te Anfl. vol. i. p. 
246), £mpedocl« (Burnet, Early Greek PhUoa. p. 230), Democritus 
(ZeUer, op, cit, p. 810), Anazagoras (cf. below 4706 20). 

^ Aristotle confined respiration to the admission and expulsion of air 
(4806 10). In modem Physiology, respiration in a wide sense includes 
that form of internal respiration (properly a function of nutrition), which 
means the interchange of oxygen and carbon dioxide between the oeUs 
and the fluid that drenches them (cf. Ency, Brit, Art on " Respiration "). 
OrdinarUy, however, it is used to signify the expulsion of carbonic acid 
and the admission of oxygen, which is effected mainly through the 
lungs, gills, skin, and alimentary canal. Pulmonary respiration is the 
chief means of working this interchange, and it is to this that Aristotle's 
opusde is confined, referring to other means of respiration as only 
analogous functions, 



is untrue. It will be necessary, therefore, to return to 2 
these points, in order that we be not thought to make 
unfounded charges against writers who are no longer 
living. It is plain that all animals with lungs 
breatha But amongst these, the animals that have a 
spongy, anaemic lung need respiration less than the 
others. Consequently they can remain, owing to their 
physical strength, a considerable time under water. All 
oviparous animals have a spongy lung, as is the case in 3 
frogs.^ Again, water-tortoises and land-tortoises can 
remain a long time under water. In these animals the 
lung has little heat, because it has little blood. Conse- 
quently when it has been once inflated, it effects refrigera- 
tion by its motion and enables the animal to continue a 
long time under water without breathing. Even in these 4 
cases, however, when the animal is forced to hold its 
breath too long, it is suffocated. For none of these 
animals can inhale water, as fishes do. All animals, 
on the other hand, whose lung is full of blood, have 
greater need of respiration, because of their greater 
heat As to the animals that have no lung at all, they 
have no respiration at all. 

^ In the frog the cavity of the lung is divided into a honeyoomb of 
chambers or alveoli. Each septum of the long, being rich in elastic 
tissne and equipped with a minute network of capiUaries covered on 
each side with epithelium, is freely exposed to the air, and owing to the 
honeycomb structure of the lung the area of exposure to the air (and 
consequent exposure of the blood) is great (of. Foster, Phynohgy, 6th 
ed. p. 667). Birds exhibit a reptilian rather tiian mammalian form of 
lung (Owen, AneUom, of Vertebraies, voL iL, p. 209). 


Democrittjs of Abdera and certain other writers on the 
subject of respiration have not spoken definitely about 
the animals last named, but they appear to assert 
that all animals breathe. Anaxagoras, however, and 
Diogenes make the statement that all animals respire, 
and they say that fishes and oysters are endowed with 

2 a sort of respiration. Anaxagoras declares that when 
471a fishes discharge water through their gills, they inhale 

the air that is developed in the mouth (for a vacuum 
does not exist), and so respire. Diogenes, on the other 
hand, says that when fishes discharge water through 
their gills, they inhale air by the action of the vacuum 
formed in the mouth, out of the water which surrounds 
the mouth, on the theory that water contains air. 

3 These views, however, are untenable. For, in the first 
place, they leave out of account half of the truth, because 
their entire statement refers only to one aspect of the 
case. For by respiration one understands partly in- 
spiration and partly expiration, and they have nothing 
to say in explanation of how the latter takes place 

4 in lungless animals. And it is impossible for them 



to give any explanation. For when inspiration takes 
place, expiration must also follow by the same 
channel as that employed in inspiration, and these two 
things most succeed each other in constant alternation. 
The consequence is that exhalation must take place at 
the same moment that water is being received into the 
mouth, and in that case the one must impede the other 
by meeting. Secondly, if they exhale by the mouth or 5 
gills at the moment when they discharge water, the 
consequence will be that inspiration and expiration will 
be simultaneous, and, according to the above assertion, 
this is the moment in which animals inspire. But simul- 
taneous inspiration and expiration is an impossibility. 
Consequently, if it is true that respiration involves both 
inspiration and expiration, and if it is further true that 
aquatic animals are not capable of expiration, it is 
clear that they are also incapable of respiration. 


Again, the assertion that they inhale air from the 
mouth, or from the water through the mouth, is im- 
possible. For aquatic animals have no windpipe, because 
they have no lung, but the stomach is inmiediately 
adjacent to the mouth, and consequently the stomach 
would necessarily be the organ of inspiration. But if 
this were true here, the stomach would have this power 
in other animals also. As a matter of fact, it does not 
have this power. Further, if aquatic animals were re- 
moved from the water they would then clearly show this 

2 capacity to respire ; but they do not show it Further- 
more, we observe in those animals that respire and 
inhale air a certain movement in the organ of inhala- 
tion. This is not observable in fishes. They appear to 
move no organ about the stomach other than the gills^ 
whether they are in the water or are thrown gasping on 

3 the dry shore. Again, when any respiring animal dies 
471 d from suffocation in the water, its breath, as it forcibly 

leaves the body, is formed into bubbles, as one sees in 
the case of tortoises or firogs, or other animals of this 
sort, when they are forcibly drowned. With fishes, 



iowever, this is not the case, whatever method one may 

because they contain no inhaled air. According to 4 

the explanation of respiration above mentioned, it would 

'be possible also for men to respire when in water. For 

lif fish inhale air from water by means of their mouth, 

why should not men and other animals do the same 

ihing ? They should inhale air from the mouth quite 5 

much as fishes. If the latter have this power, the 

rmer should have it also. But as this ia not true in 

le one case, it evidently does not hold good in the 

:her. Furthermore, if fishes respire, why is it that 

'e see them die in the air and gasp as if suffocated ? ' 

It is not owing to lack of food. The explanation given 6 

by Dic^enes is foolish. He says that fishes, when in the 

air, inhale too much air, and this is why they die, whereas 

in the water they inhale a moderate amount But this 

should then be possible for land animals also. In point of 

fact, no land animal is suffocated by excessive inhalation. 

t^nrther, if all animals respire, insects must evidently ^ 

ipire also. Many of them, however, seem to live 

Lewes {Ari^otlt., p. 170) uya that th« re&aon why dsh die in the 
whsD he wrote the Dote (1364), itill awaiting an eiplsDation. 
then not BatiaSed with the explanation of Flourena i,AiiwtU» 
nea naturfUfJi, IBSO), which sttributed enffocation to the 
Golhipae of the gills in the &ir. >□<! the conseqaeDt inadequate aeration 
of blood, which do doubt ii the chief oanae, and Lewea' experiment in 
artijicially aeparatiag the leaflets of the gilU would not leem to be 
any adeqoate disproof. The namber of reBpiratiooB per minute in 
water has been experimentally inveatigated by McKeadrick [JoamcU 
of Anatomy arid Physiol, vol. xiv. 1879, p. 463) and toond to vary in 
different liBhes, ranging from 15 reapiiutioDB (Rockling and Blue 
Wraaae) to 120 (Minnow and Stickleback). It is, however, no doabt 
true that rapid deiiccation is a farther cause of the dying of flsh in 
the air, and the protection againat this by the coat of iltme on «eli 
explain! their living longer. 


when they are divided, not only when divided into 
two parts, but into several, as in the case of the centi- 
pedes. How or by what oigan is it possible for these 
8 parts to breathe ? The chief cause of the error of 
these writers was their ignorance of the internal organs, 
and also the fact that they did not grasp the truth of 
design in nature. For by asking to what end animals 
are endowed with respiration, and by making a test of 
their theory on the oigans themselves, as, t,g.^ on the 
gills and lungs, they would soon have discovered the 
real explanation. 


Democritus makes the statement, it is true, that respira- 
tion produces certain effects in the respiring animal, viz. 
it prevents the soul from being expelled from the body. 
He by no means says, however, that nature in creating 4720 
this function did so with this end in view. For he is, 
on the whole, like the other physicists^ and makes no 
application of any such causality. He maintains that the 2 
soul and heat have one and the same nature, viz. they are 
elemental spherical atoms. Consequently, when these are 
compressed by the force of the surrounding air, inhalation 
comes to their assistance. For in the air there is a large 3 
number of the atoms which he calls mind and souL In 
the act of inhalation, then, and along with the entrance 
of the air, these atoms also enter, and, by counteracting 
the pressure, prevent the expulsion of the soul that 
resides in the animal body. It is for this reason that 4 
life and death depend upon inspiration and expiration. 

^ We &re almost entirely dependent on this aoooont of Aristotle for 
theories of respiration amongst the Presocratics. For the theories of 
Galen and Hippocrates see the article of Steinheim, " Antike Lehre d. 
Athmens " in LiU. Ann. d, guamm. Heilkunde, voL x. (1S2S), p. 267 ff. 


294 Aristotle's psychology di 

For when the surrounding medium by its pressure gains 
control and the outer air is no longer able to enter and 
counteract this control, respiration in the animal becomes 
impossible and death ensues. For by death one means 
the departure of these psychical atonus from the body due 

5 to expulsion by the surrounding medium. The reason, 
however, why death necessarily comes at all to every 
animal, and why it does not come at any chance period, 
but in the course of nature only in old age, — a violent 
death is contrary to nature, — he has not in the least 
explained. And yet, because this phenomenon occurs 
evidently at one period and not at another, it behoved 
him to explain whether it is due to an external or to an 

6 internal cause. Further, he has not a word to say 
regarding the origin of respiration, whether its cause is 
external or internal And yet it is evidently not the 
external mind that comes to the rescue here, but the 
principle of respiration and of respiratory movement is 
due to an internal cause, and we are not to suppose that 
the force of the surrounding medium is any explanation. 
It is also absurd to think that the surrounding medium 
has at once the effect of extinguishing by compression, 
and on its entrance the opposite effect. The foregoing, 
in content and manner of statement, conforms closely to 

7 the theory of Democritus. If one is to regard as true 
what was said a while ago, viz. that not all animals 
respire, then we must regard the Democritean explanation 
of death as not universally applicable, but only to those 
cases where animals breathe. But even to these cases it 
does not well apply, as is evident from facts observed by 

8 all of u& For in warm weather, when we are more than 


usually heated, we have greater need of respiration and 
we all breathe more rapidly. When, however, our 
environment is cool and contracts and chills the body, 
we hold our breath. This is the very moment, however, 9 
that the air from without should enter and prevent the 
soul's expulsion. In point of fact it is the opposite that 472^ 
takes place. For when excessive heat is accumulated, 
owing to its not being exhaled, that is the moment we 
need respiration, and inhalation is necessary to this. The 
truth is, men breathe rapidly when they are hot, because 
respiration has a cooling effect, at the very moment 
when ([according to the theory of Democritus]) they would 
be, to use a proverb, ' adding fire to fire.'^ 

^Because Democritaa regards the soul-atoms as identical with the 


The theory of circular push described in the Timaetu^ 
gives no explanation whatever of the way in which heat 
is maintained in animals other than man, whether the 
preservation of heat in the various animals is due to the 
same or different causea For if the phenomenon of re- 
spiration is found in land animals alone, we must explain 
why they alone breathe. If, however, it occurs in other 
animals also, but by a different process, assuming that 
they can all respire, we must find an explanation for the 
2 difference in process. Furthermore, the whole manner 
of explaining the phenomenon is fanciful For Plato 
says that by the issuance of hot air from the mouth, 
the surrounding air is pushed forward and is transmitted 
through the pores of the flesh, and rests at the point 
from which the internal hot air issued. These elements 
thus effect a complementary displacement, owing to the 
fact that a vacuum is impossible. In the same way the 

^ TVmoetM, 79 A ff. Plato's explanation of the circular movement of 
inspiration and expiration is expressly applied by him to the lowering 
of animal heat, and not only in man but in all animals, as he says, " in 
the interior of every animal the hottest part is that which is aronnd 
the blood and veins " {TimaeuSf loc, cU.), 


CHAP. V. Plato's theory 297 

inhaled air in turn, when heated, is discharged and the 
warm air within, issuing out through the mouth, continues 
this ' circular push.' And so this process, which is inspira- 
tion and expiration, goes constantly on. The logical 3 
consequence of the theory is that expiration precedes 
inspiration, whereas the opposite is the fact, as the 
following proves. The two things are correlated 
phenomena. Now man's last act is expiration, conse- 
quently inspiration must form the beginning. Further, 4 
the end which these processes (I mean inspiration and 
expiration) subserve in the animal body is not taken into 
account at all by the philosophers who advocate this 
theory. They treat them merely as unessential phe- 
nomena. We see, however, that they are the master- 
factors in life and death. For when a breathing animal 
is unable to respire, at that moment death ensues. 
Further, it is absurd to suppose that the issue of hot 5 
air through the mouth and the entrance of air again 
by the mouth should be observable by us, whereas 
the entrance of the breath into the thorax and its 
discharge should not be observable.^ It is also strange 
that respiration should mean the introduction of 
heat.^ Observation shows the contrary, for expired air is 6 
hot, whereas inspired air is cooL And when the 
atmosphere is warm animals pant in respiring and they 
draw their breath frequently, because the entering air 473 << 
does not adequately cool them. 

^ That is through the pores into the thorax. 

* Respiration to Plato means the introdnotion of heat only in so 
far as it means the maintenanoe of heat and the snpply of fael 
(TtmaetM, 79 B). 


We must also reject the theory that the purpose of 
respiration is nutrition, which presupposes the feeding 
of internal heat bj means of the breath. According 
to this view, inspiration is similar to throwing fiiel on a 

2 fire, and expiration follows when the fire is fed. We 
again urge the same objections to this theory as we did 
to the theories enumerated above. The same process, 
or something analogous to it, should be found in all 

3 animals, for they all have vital heat. In the next place, 
the advocates of this theory should explain how heat is 
generated out of the breath. The whole view is fancifuL 
According to our observation generation of heat is due 
much rather to food. A further consequence of their 
theory is that food is received and excrement discharged 
at the same orifice,^ which is not seen in any other 

^ The reference may be to the Pythagoreans (of. Dt miuu 440a 16), 
who auerted that oertain animalii are fed by the Inspiration of smells. 
Bat we have no details about their doctrine. Inasmach, however, as 
food here appears to be fnel for vital heat, the reference to Plato is 
possible, who in the ' cironlar posh ' theory would seem to admit food 
and discharge waste by the same orifice. 



Empedoclss also has a theory of respiration, although 
he does not explain the purpose of respiration, nor does 
he say definitely whether all animals are endowed 
with respiration or not In treating of respiration 
through the nostrils, he fancies he is dealing with 
the main factor in this process. He is here mistaken, 2 
for there is respiration through the windpipe, which 
leads from the chest, as well as respiration through 
the nostrils, and without a windpipe the nostrils 
themselves could not respire at alL Animals may even 
be deprived of respiration through the nostrils and suffer 
no harm, but if the use of the windpipe is shut off they 
die. In certain animals, indeed, respiration through the 
nostrils is employed by nature for the secondary function 3 
of smelL Although almost all animals are endowed with 
the sense of smell, they do not all employ the same organ 
for this purpose. On this subject, however, we have 
spoken elsewhere more in detail^ 4 

Empedodes asserts that inspiration and expiration take 473 ^ 
place through particular veins, in which there is blood, 

^Ct. Dean, 421a 7 tL ; De ienm, 4446 16. 


300 Aristotle's psychology derbsfol 

although they are not entirely filled with blood, and that 
these veins are provided with channels that lead into the 
outer air, channels which are too minute for the admission 
of crass matter, but large enough for air. Now, the blood 
is so constituted as to move up and down, and after its 
downward motion the air streams in and inspiration takes 
place ; on its upward motion expiration into the outer air 
ensues — a process which resembles what we observe in 
the Clepsydra : ^ 

5 Thus all things breathe and breathe out air again. 

Long bloodless tubes the body's surface reach, 
And at their close-packed vents are nostrils fixed 
Pierced through ; and so a passage way is cut 
For air, while yet the blood is hidden held. 
When yielding blood along these channels ebbs, 
Then bursts the surging air with tempest's wave 
Within. But when the blood rebounds, the air 
Is then expired again, as one may see 
A child with smooth bronze water-clock at play. 
Upon her comely hand she sets the tube. 
And dips it in the yielding water's sheen, 
Of which no drop slips in the vessel's form. 
Upon the close-packed vents the air doth press 
Within, until the maid her hand removes 
And frees the urgent stream, which entrance makes, 
Whose even flow drives back the yielding air. 
So, too, when e'er the waters full free flow 
Hath filled the deep bronze tube, and maiden hand 
The passage firm hath blocked, then doth the air. 
The eager outer air, the vents make fast 
And hold in its restraint the inner stream 
Whose waters at the narrow gates complain, 
474 a Until the maiden lifts her hand. And now 

Is true the converse of what was before : 
The air flows in — the water's equal stream 

^ Buraet {Early Oreek Phihs, p. 230) gives a valuable elucidation of 
this passage. 


Flows out. Thus also 'tis with fluent blood 
That coursing through our limbs now hurries back 
To inner depths, and straightway air pours in 
With surging swell Again the blood returns 
From its retreat ; then forthwith yields the air, 
Exhaled once more, in nature's even course.^ 

These are his words on the subject of respiration. As 6 
we have already said, animals that visibly respire do so by 
means of the windpipe as well as by means of the mouth 
and nostrils. Now, if Empedocles is speaking of respira- 
tion in this sense, we must inquire how far his explanation 
harmonizes with the facts. Apparently the facts con- 
tradict his theory. For in inspiration the receptacle is 7 
expanded like a brazier's bellows. Expansion, however, 
is naturally explained by heat and by blood which takes 
the place of heat ([but it is not explained by air in the 
theory of Empedocles]). In expiration, on the other 
hand, contraction and collapse take place, as in the 
bellows, excepting that the cases are not quite parallel in 
this respect, viz. the bellows do not admit and discharge 
air by the same orifice, whereas in inspiration and expira- 
tion the same orifice is used. If, however, he is here 8 
referring merely to respiration through the nostrils, he is 
quite wrong. For respiration is not a function which is 
peculiar to the nostrils; on the contrary, along the 
passage near the uvula, at the extreme end of the roof of 
the mouth, part of the air passes here through the 
openings of the nostrils and part of it through the mouth, 
and this applies equally to inspiration and expiration. 

^ VuL Fragments of Empedocles in Mallach's Fragmenta PHUm. 
Orate, (Paris, 1883), vol. i., pp. 10, 11. 


It was said above that life and the possession of soul are 
accompanied by a certain degree of heat^ For even the 
process of concoction, by which food is prepared for 
animal life, cannot be accomplished without soul and 

2 heat ; all this is effected by fire. Consequently, such a 
fundamental process as this must be situated in the 
primary region of the body and in the primary organ of 
this region, and here it is that we must look for this 

474 ^ elementary nutritive souL This is the middle region 
between the orifice for admitting food and that for 
discharging excrement. In bloodless animals the primary 
organ has no name, in sanguineous animals it is the heart 

3 The food out of which animal members are generated is the 
blood. The blood and blood-vessels must have the same 
starting-point For the one, as vessel and receptacle 
exists for the other. The originating point for these 
vessels in sanguineous animals is the heart They do not 

4 traverse the heart; they all issue from it and are 

^Even plants, Aristotle oorreotly remarks (slthongh he gives no 
reason for the statement), exhibit vital heat {De pari, an, 600a 6 ; Dt 
vU. €i mart 470o 22). 




f attached to it, as is evident from dissection.i Now, the 
other functions of the soul cannot be performed indepen- 
dently of the nutritive principle (the reason for which 
I bag been stated in the treatise On the Soul),^ and the 
[ Dutritive principle in turn cannot subsist without natural 
[ heat. For it is through natural heat that nature has 
I endowed the nutritive principle with warmth. Fire may 
I be destroyed, as we said before, in two ways : by extinc- 
I tion and by exhaustion. Kxtinction is effected by opposing s 
I forces, Consequently even when the fire is massed it may 
I be extinguished by environing cold, and when scattered it 
more easily quenched. This extinction by external 
I force applies to animal heat as well as to inanimate fira 
I For animals die when dismembered by instruments or 
I when congealed by excessive cold. Jixhaustion, on the 6 
I other hand, follows from excessive heat. For if the sur- 
I lounding heat is great, and the internal supply of fuel is 
I sot maintained, the fire ceases to burn, not from extinction 
I by cold, but from exhaustion. Consequently there must 
le cooling process, if survival is to be attained ; for 
^tiiis comes to the rescue and prevents extinction, 

'There ia do doubt that Aristotle pr>cti««d disMction of anlniKti. 
W although he probably never dissected the humaa bodf. Hia coDclnsioai 

■ fn reference to the latter were drawn trooi the anatomy of other 

■ Miiinals, wbenee also the Aiclepiada derived their knowledge, and hia 
n are anch a« are due to this aoorce of infonnatioti and to hia apecn- 
'e views aa to anatomical atructares (e.g. the bloodleaaneaa aS the 
n, ita not extending to the back pari of the akull, and ita function 

■ a oooling apparatua). Further, Che feelings of the Greeks regarding 

« aaoredncM of the bnmao body were moah atronger than ours, and 

Bwither Hippocnttea nor Galen ia supposed to have diiBeeted man. 

~~. Siti. an. i»ib 22, blSa 12; Huxley, IfaCurt, vol. xxi. ; LewM, 

B^riatoUc, p. 165. 

*I>tan. 416a 10 ff., 434a 22. 


SoifE animals are aquatic and others have their existence 
on the dry land. In the case of the very small and 
bloodless specimens of both classes, the cooling produced 
by their surroundings, whether air or water, is adequate 
to protect them against the above-mentioned extinction. 
For being endowed with little heat they need little 
protection. Animals of this kind are, consequently, in 

2 the rule short-lived, for a slight change on one side or 
475 d( the other destroys the balance. The longer lived insects 

(which, like all insects, are bloodless^) have a fissure just 
below the middle part in order that cooling may be 
effected through the membrsme, which at this point is 
very thin. For inasmuch as they have more heat they 
have more need of cooling. Bees, for example, some of 
which live as long as seven years, and the other insects 

3 that hum, such as wasps, cockchafers, and locusts, belong to 
this class. They produce this noise by their breath, as if 

^The blood of insects is ordinarily a coloarless liquid, sometimes 
yeUowiah or greenish, and rarely red, and was not regarded by Aristotle 
as blood. Of. Owen, Compar. Anatom. wild Physiol, qf Invert. An. 
p. 3S3. 




f panting. Aa the natural breathing within rises and 

, it produces Miction against the membrane io the 

iiiddle region. For insects keep this region in motion 

ist as animals that breathe the outer air' maintain 

IDolton by their lungs or fishes by their gills. This 4 

■motion is similar to what would take place if one should 

iBoffocate a respiring animal by holding its mouth; For 

I &en this swelling movement would be produced by the 

In the latter case, however, such motion is 

I inadequate for cooling, although it is adequate in the S 

f case of insects. By means of friction against a membrane 

they produce a humming noise, as we said, in much the 

L same way as children make a noise through a perforated 

I Teed after stretching a thin membrane in it.* And it is in 

L this way, too, that the singing locusts produce their song. 

I They possess greater heat than other varieties, and have a 

in the middle region. In the songlesa locusts this 

I fissure ia lacking. Sanguineous animals endowed with 6 

I Inngs that contain little blood and are spongy, can live 

I a long time without respiration, because the lungs are 

I capable of great expansion, containing as they do 

I little blood or fluid. Consequently, their own peculiar 

' All iaseeta breathe air, which entera chiefly through the thoracic 

ad tint abdominal spirsclea. In the ewe of insects living is the lrat«r 

apiration iB effected by branchiae or falsa gilla, which me supposed to 

' absorb air from the water. Cf. PookBrd, The Study of Ituactn, p. 40 ; 

Owen, Compar. Anaiotti. and Phj/tioi. of Ou. Inetrt. An., p, 358. 

'Insects produce sounds by the vibration of their viiDf(s, by the 
vibration and friction of the abdominkl segments, and by robbing 
the head against the anterior wall of the- thorax. The shrilling of the 
male crickoC (a aexnal call) is produced by the Fricttoa of the fore wings 
against the hind wings (cf. Packard, The Study of Inieets. pp. 362, 56.t), 
Aristotle further describes the methods by which insscts prodnoe 
■oQiids in the ^ift. Jnim,, 535b 4 IT, 

306 Aristotle's psychology dbrbpib. 

motion is adequate for cooling through a considerable 

7 period. Finally, however, it is unable to continue this, 
and without respii*ation it suffocates, as we said befora 
That form of exhaustion which consists in destruction 
through lack of cooling is called suffocation, and animals 
that die in this way are said to be suffocated. We have 

8 already remarked that insects do not respira One can 
observe this plainly in the case of small insects, such as 
flies and bees, for they can swim a long time in a liquid, 

475 b provided it is not too hot or too cold. And yet animals 
which have less strength require more frequent respira- 

9 tion. They are destroyed, however, and are suffocated, 
as we say, when the belly is filled with water and the 
heat of the middle region quenched. From this we can 
understand how it is that such insects get up again after 
being covered for some time with warm ashes. We also 

ID observe that bloodless aquatic animals live in the air 
longer than do sanguineous animals that take in sea- 
water, as the fishes. For the former have little heat, and 
consequently the air is adequate to cool them for a 
considerable time, as is the case with Crustacea and 

II polyps. And yet it is finally inadequate for life, because 
they possess little heat; for even fishes are often dug out 
of the earth and found to be living, although motionlesa 
Animals that are endowed either with no lungs at all or 
with lungs containing little blood, need the least frequent 


In rq[ard to bloodless animals we have said that some 
of them owe their survival to the surrounding air, 
others to the water. Tn the case of animals that have 
blood and a heart, all those that are provided with 
lungs take in air and effect cooling by means of inspira- 
tion and expiration. Now, viviparous animals are 2 
provided with lungs, not those, however, that bear their 
living young outside of themselves (for the cartila- 
ginous fishes are viviparous, but not within their own 
bodies'), and amongst oviparous animals those that 
have wings are provided with lungs, as, e.g. birds, and 
further, such animals as have scales, like the tortoises, 
lizards, and snakes. Viviparous animals have a lung well 3 
filled with blood, whereas most of the oviparous animals 
have spongy lungs. Therefore, as we said before, the latter 
need less frequent respiration. All of them, however, 4 
do breathe, even those that live and maintain their 
existence in the water, such as hydras, frogs, crocodiles, 

^Mammalia are Aristotle's "internally viparoas.*' By "externally 
viyiparous" he means the OTOTiparons, which are witboat placental 


308 Aristotle's psychology dibwpir. 

fresh-water tortoises, tortoises of the sea and land, and 
seals. For all of these animals, and others similar to them, 
bear their young on the land, and sleep either on land 
or in the water with their mouths above the surface 
4760 for respiration. Animals, on the other hand, that have 

5 gills, are cooled hj taking in water. To this class 
belong the cartilaginous fishes and other apodous animals, 
including all fishes. For their organs of locomotion are 
after the analogy of wings ([rather than feet]). Amongst 
animals that have feet, only one, so far as has been 

6 observed, has gills, viz. the tadpole, as we call it But 
no case has ever been seen of the possession of lungs 
and gills together. The reason is that the lungs are 
designed for cooling by the admission of air (even the 
name irueu/jLUiv, 'lungs,' seems to have been derived from 
their reception of irveSjuui, ' air '), and gills are designed 
for cooling by the admission of water. But only one 
organ is used for one purpose, and one method of 

7 cooling is adequate for each animal And so, since 
we know that nature makes nothing in vain, and since 
one of these two organs would be useless, some animals 
are provided with gills and others with lungs, but no 
animal with both.^ 

^Ogle {op, cit, p. 125) points out that Aristotle cannot have been 
acquainted with the Dipnoi or Amphipneusta, in both of which groups 
gills and lungs co-exist. 


SiNCB every animal needs food for its subsistence and 
cooling for its persistence, nature employs for these 
two purposes one organ.^ And as in some ftnimftl^ 
the tongue is employed for the double purpose of tasting 
and communicating thought, so in those which are 
provided with lungs, the mouth serves for the masti- 
cation of food as well as for inspiration and expiration 
of air. In those, on the other hand, that have no 2 
lungs and do not respire, the mouth serves for the 
mastication of food, but giUs are provided for cooling 
where cooling is needed. In what way the functioning 
of the aforesaid organs effects cooling, we shall explain 3 
later. In order not to hinder the admission of food, 
a similar method is employed by respiring animals and 
by those that take in water. For in the former case 
they avoid respiring and swallowing their food at the 
same instant, otherwise they would choke by admitting 
liquid or solid food into the lungs through the windpipe. 

>Cf. De part. an. 660a 22, 683a 19 fL ElMwhere Aristotle refers 
also to the nostrils as organs subserving respiration. De part. an. 
6406 16, 660a da Cf. also above 478a 17 ft 


310 Aristotle's psychology dbrespis. 

For the windpipe lies in front of the oesophagus, through 
which food finds its way into the stomach. In the 

4 sanguineous quadrupeds the windpipe is provided with 
a sort of lid called the epiglottis. In birds and ovi- 

A76b parous quadrupeds, on the contrary, there is no such 
lid, but they attain the same end by contracting the 
windpipe.^ When food is being swallowed, the ovipara 
contract the windpipe, whereas the vivipara close the 

5 epiglottis. And after the food has passed, in the one 
case the windpipe is expanded, and in the other the 
epiglottis is opened, and air is admitted for the purpose 
of cooling. In regard to those animals that are pro- 
vided with gills, they discharge the water through 
these and then admit food through the mouth. They 
have no windpipe, so that they can suffer no harm 
by the wrong discharge of water into it, but only by 

6 the entrance of water into the stomach. For this 
reason, the discharge of water and the swallowing of 
food is done rapidly, and their teeth are sharp, and 
in almost all instances are serrated, for they cannot 
chew their food. 

^ In the mammalia food U prerented from passing into the windpipe 
during deglutition by the epiglottis, which is possessed by no other 
animids, while in other vertebrates this function is performed by the 
closing of the larynx through muscular constriction {Dt part, an, 
0646 22). Of. also Hist, an, 535a 29 £ and De an. 4206 29, where the 
functions of these organs in speech are treated. 


REGABDiNa the cetaceous aquatic animals, such as dolphins, 
whales, and such others as have what is known as a spout- 
organ, one might feel some doubt, yet even these conform 
to our theory. For they are apodous, and although they 
have lungs they take in sea-water. The ground for this 
apparent exception is given in the foregoing explanation ; 
for the end to which they take in water is not cooling. 2 
This is produced in their case by means of respiration, for 
they have lunga Consequently, they sleep with their 
mouths above the water's surface, and dolphins, it is 
certain, snore. Again, when they are caught in nets, they 
soon suffocate from lack of respiration. It is in order to 
breathe, then, that we observe them lying on the sea's sur- 
face. Since, however, they are forced to take their food in 3 
the water, they must on swallowing discharge the water, 
and for this reason they are all provided with a spout-organ. 
When they have taken in water they discharge it through 
this spout-organ, just as fishes do through their gills. A 
proof of this fact is the position of the spout-organ. It 4 
does not lead to any of the blood-fiUed organs, but is 

situated in front of the brain and discharges the 


312 AMSTOTLE's psychology dk 

water ^ here. For the same reason the molluscs and 
crustaceans admit and discharge water. I mean the sea- 
crayfish and crabSy as we call theuL They make no use of it 

5 for cooling, for they are endowed with only a small amount 
of heat and are in every case bloodless, so that they are 

477 « kept cool enough by the surrounding water. But it is 
dischai^ged on account of their food, viz. in order that the 
water may not enter at the moment of swallowing. The 

6 crustaceans, such as the sea-crayfish and crabs, discharge 
the water through the plaited folds along their shaggy 
covering; the purple fish and polyps discharge it 
through the hollow passage above the head These 

7 questions have been treated with greater detail in the 
History of AnimcUs} Concerning the phenomenon of the 
admission and discharge of water, we have said that it is 
due, in certain cases, to the need of cooling, and in others 
to the fact that aquatic animals are obliged to swallow 
their food in the water. 

^Ogle {op, eit. p. 127) cites Cuvier {Bigne animal, i. 285) as giving 
the same explanation of the purpose of the blowhole, and says it ia atiU 
the popularly reoeived, although erroneous, view. Its actual use ia to 
provide an additional safeguard (besides the epiglottis) against the 
entrance of water into the air passages. 

s^isf. aii.525a30ff. 


We must next describe the method by which cooling is 

effected in respiring animals and in those provided with 

gills. We have already said that animals which have 

lungs respire. As to the reason why some animals have 2 

this organ and why those that have it need respiration, it 

is because the higher order of animals are endowed with 

greater heat. At the same time it must be that they are 

endowed with a higher order of souL For such beings 

are of a higher order than plants. Consequently, animals 3 

whose lungs are more abundantly supplied with blood and 

heat are of greater bodily dimensions than others ; and 

the animal that is supplied with the purest and most 

abundant blood, i.e, man, is the most erect of all animals, 

and his upper structure points to the upper r^on of the 

universe — true of him alone — because he has lungs 

constituted as we have described. The essential character 

both of man and of other animals must, therefore, be 

ascribed as much to this as to any other organ. This, 4 

then, is the purpose of the lunga One must suppose that 

the material conditions and moving cause have constructed 

these animals in this way, as they have also operated to 



produce other animals with a different constitution. For 
some are composed chiefly of earth, like plants, others 
chiefly of water, like aquatic animals. And amongst the 
winged and terrestrial animals, the one class is composed 
chiefly of air and the other of fire. And they severally 
have their place in regions akin to their own naturea 


Empedocles^ wa8 wrong in saying that the aquatic 
animals are warmest and contain most fire, and, being 477^ 
defective in cold and fluid, they seek refuge from 
constitutional excess of heat in a medium to which 
their nature is opposed. For water is cooler than air. 
It is, however, altogether unintelligible how animals bom 2 
on dry land can change their place of abode to water. 
For they are, in almost all cases, apodoua And yet, 
when speaking of their primary constitution, he asserts 
they are bom on the dry land and later leave this and 
migrate to the water. Again, our observation shows 3 
that they are not warmer than land animals; for some 
of them are absolutely bloodless, while others are almost 

^The writiogs are no longer extant from which Aristotle derived 
these views of Empedocles. Lucretius, who was a foUower of 
Epicurus, and an admirer of Empedocles (cf. Dt rer, not. i. 66, 716 ffl), 
gives expression to the same view {Dt rer, not, v. 793), that land 
animals cannot have migrated from water {aaJUia lacunia) to the land ; 
on the contrary, all animals are land-bom (a terra quaniam eurU cuncta 
creata). The theory of Empedocles was allied to tJie ancient myth of 
the Autochthons. Anaximander, on the contrary, taught the evolution 
of animals from the moist element under the i&flnenoe of the sun*s 
heat (Bitter and Preller, PhHo9, graee, p. 19a). 



80. But what kind of animals we should call warm and 
what kind cold, is a subject itself that requires investiga- 
tion. Eegarding the explanation given by Empedocles, 
his contention is, in a certain sense, correct, although 

4 what he says is not entirely true. For it is true that 
regions and seasons which exhibit characteristics opposed 
to abnormal conditions in animals tend to preserve them, 
and yet their normal nature is best preserved in a place of 
abode similar to their own constitution. For the matter 
out of which animals are severally constituted must not 
be confounded with the varying states and conditions of 

5 this matter. I mean, e,g. if a thing were formed of 
wax or ice, its preservation would not be secured by 
placing it in a hot environment. For, owing to the 
opposed nature of its surroundings, it would be quickly 
destroyed, for heat melts that which consists of the 
contrary nature. Again, if a thing were composed of 
salt or nitre, nature would not carry it and set it down 
in a wet environment, for water dissolves substances of a 

6 warm, dry constitution. If, therefore, the fluid and solid 
constitute the matter out of which all bodies are formed, 
it is reasonable to suppose that fluid and cold structures 
will be found in a moist environment; solid structures, 
on the other hand, in a solid environment Consequently, 
trees do not grow in water, but in the earth; although, 

7 according to this same theory of Empedocles, they should 
migrate to the water, because of their being predominantly 
dry, or, to use his expression, "predominantly fiery." 
This migration would be to water not because it is cold, 
but because it ijis fluid. The natural constitution of 
matter, therefore, conforms to the environment in which 


it is found — ^the moist, t,g. is found in water, the warm 8 
in the air. Acquired conditions, however, are better 47Sa 
regulated through an opposite environment, excessive 
heat through cold surroundings, and excessive cold 
through warm surroundings. For the environment 
reduces the excess in these conditions and brings them 
to an equable mean. This reduction is to be sought in 
an environment adapted to the particular constitution 
of the thing and in the variations of ordinary climate. 
For acquired conditions may be opposed to the place 
of abode, but this is impossible in the case of the original 

Touching the theory of Empedocles that animals are 9 
divided into aquatic and land animals on the basis of 
differences in natural heat, and touching the explanation 
of the phenomenon that the one class has lungs and the 
other not, let the foregoing discussion suffice. 


The reason why animals with lungs can take in air 
and respire, especially such as have lungs well filled 
with blood, is to be found in the fact that the lungs are 
porous and filled with tubes. The lungs contain more 
blood than any other organ in what we call the viscera. 

2 Animals whose lungs are abundantly supplied with blood 
need rapid refrigeration, because of the delicate balanc- 
ing of the natural heat, and because the cooling process 
must penetrate through the entire interior, owing to the 
great supply of blood and heat. Air can easily meet 
both these demands. For owing to its rarity, it rapidly 
penetrates everywhere, and effects cooling.^ This is not 

3 true of water. It is also plain from this why it is that 
animals which have lungs well filled with blood breathe 
best. It is due to the fact that the warmer the nature 
the greater is the need of cooling, and at the same 
time that the air fills the lungs, it passes readily to the 
original source of animal heat in the heart. 

^ Empedocles and Plato supposed that the air penetrated through the 
pores of the skin, which in their theories became channels of venti- 



Thb way in which a passage is made between heart 
and lungs must be studied through dissection, and in the 
History of Animals} Animal nature, in general, needs 
cooling, because of the vital fire in the heart. This is 
accomplished by means of respiration, excepting in those 
cases where animals are provided with a heart only but 
no lungs. When they have a heart but no lungs, as is 2 
the case in fishes, whose natural abode is water, cooling is 
attained by water through the use of the gills. In regard 
to the relative positions of heart and gills, one must study 
them ocularly in dissection and their nicer philosophy in 478^ 
the History of Animals. To give a summary descrip- 
tion, however, the case is as follows : One might suppose 3 
that the position of the heart in land and aquatic 
animals was different ; as a matter of fact, it is the 
same in both. For the direction in which the animal's 
head naturally inclines is the direction in which the 
heart's apex is turned. But inasmuch as the heads of 
land animals do not incline in the same direction as 

'Cf. HiiL an, 498a 6 ff., 5116 24, where an historical aoooant of 
theories regarding the anatomy of the blood-dnoia is giren. 



those of aquatic animals, the heart's apex in the latter 

4 case is turned towards the mouth. A sinewy vein-like 
tube extends from the extremity of the heart^ to a 
central point, where all the gills are united. This is the 
largest of all the tubes, but there are others on each side 
of the heart which extend to the several extremities of 
the gills, whereby cooling is produced and transmitted 
to the heart, the water being constantly piped through 

5 the gills. The rapid swelling and falling motion of 
the thorax in inhaling and exhaling air serves the same 
purpose in respiring animals that the movement of gills 
does in fishes. Bespiring animals suffocate in a small 
quantity of air that remains unchanged ; for each medium 
([water as well as air]) soon becomes hot, and contact 

6 with the blood heats them. When, however, the blood 
becomes hot, the process of cooling is impeded. Also 
when respiring animals become unable to inflate their 
lungs, or aquatic animals to move their gills, whether 
owing to disease or to the weakness of old age, their 
end must be at hand. 

^ The aortic bulb, which Aristotle took to be the heart's apex. 


BiBTH and death are phenomena common to all animals, 
although there are specific differences in their modes of 
occurrence. Death is not everywhere the same, although 
in its varied forms there is a common element. Death 
ensues from violence or from the ordinary course of nature. 
Death is violent when due to an external cause, natural 
when due to internal processes. The latter conforms to 
the original organic structure, and is not an adventitious 
condition. In plants this process is called decay ; in 2 
animals, senility. Death and decay attach to all organ- 
isms alike that are complete, and to the incomplete also, 
but in a different way. Under incomplete, I understand 
such things as eggs, and seeds of plants which as yet 
have not taken root. Death is caused in all things by 
lack of heat ; in complete organisms by its failure in that 
part where the vital principle is lodged. This principle 3 
is lodged, as we said above, in the middle region, where 
the upper and lower parts are conjoined. In plants it is 
the point at which stem and root unite ; in sanguineous 
animals, it is the heart ; in bloodless animals, in an organ 479 a 
analogous to the heart. In some of the bloodless animals 

X 321 

322 Aristotle's psychology de bsspib. 

we find many vital centres potentially, though not 

4 actually. For this reason certain insects, when divided, 
continue to live, and such sanguineous animals as are not 
highly organized live a considerable time after the removal 
of the heart, as is true of tortoises. Tortoises continue to 
move their feet^ so long as their shell is not removed, 
because their organization is of a lower order, resembling 

5 in this respect the insects. The vital principle succumbs 
in its possessor when the heat which is its accompaniment 
is not reduced by cooling. For otherwise, as we have 

6 often remarked, it is consumed by its own agency. When, 
therefore, the lungs or gills respectively become hardened, 
or dried up and earthy through lapse of time,^ it is 
impossible for these organs to function, to dilate and 
contract. And finally, when a further demand is made 

7 upon them, the fire of life is extinguished. Consequently, 
death quickly ensues in old age, even on the appearance 
of trivial ailments. This is due to the fact that 
there is little heat left in old age, most of it having 
been exhaled in a long life, and if any extra strain 
is put upon the lungs, life is speedily quenched. 
For the fire within, being now but a tiny feeble 

8 flame, is extinguished by a slight movement. That is 
also the reason why death in old age is painless, for 
death comes to the aged with no element of violence 
in it, rather the dissolution of the soul occurs quite 

9 without their feeling it Diseases which make the lungs 

^Ogle {op. cU, p. 132) points out that this passage shows that 
Aristotle occasionally vivisected animals, and dtes the following 
passages : Hist. an. 5036 23; De gen. an. 766a 26, 7746 31. 

' Or through the hardening (by drying) effects of fever or accretions 
of matter on the longs' surface. 


hard, whether by tubercles or deposits or by excessive 
morbid heat, as in fevers, produce an acceleration of the 
breathing, because the lungs are incapable of full expansion 
and contraction. And finally, when motion is no longer 
possible, men exhale their breath and die. 


Birth, then, is the original sufiusion of the nutritive soul 
with heat, and life is the maintenance of this heat. 
Youth is commensurate with the growth of the primary 
organ of cooling, old age with the wasting of the organ, 
and the prime of life with the middle period between the 

2 two. Death and violent destruction mean respectively 
the exhaustion ^ and extinction of the vital heat (for it is 

479 ^ destroyed from both causes) ; exhaustion is given in the 
nature of the thing itself, and is caused by lapse of time 

3 and by the completion of a normal term of life. In 
plants this is called decay ; in animals, death. Death in 
old age is due to the exhaustion of the organism that 
comes from senile inability to effect cooling. We have 
now explained the meaning of birth, life, and death, and 
have treated the causes of these phenomena in animals. 

^Extinction {jp^u) is violent or artificial; exhaoition {jidpa»ffif) is 
natural or dae to the inherent nature of the thing itself. Cf . De vit, et 
mort, 4696 23 ; De resp. 4746 14. 



Fboh these considerations one may clearly see why it is 
that respiring animals are suffocated in water, while 
fishes are suffocated in the air.^ For in one case cooling 
is effected by the medium of water ; in the other by that 
of air, and both of them are deprived of this by the 
change in their place of abode. We have further to 2 
explain the movement ^ in gills and lungs respectively, — 
exhalation and inhalation in the one case, and the 
admission and discharge of water in the other. We 
have also to explain the structure of the organ of 
respiration in what followa' 

1 Vid. note 1, p. 291. 

't.e. by the moTements of these organs the cooling medium (air or 
water) is admitted to the organism and the temperature regolated. 

'The explanation foUows in Chapter xxL Ogle (p. 132) considers 
Chapter xx. an interpolation. 



There are three phenomena regarding the heart, which 
might be supposed to have the same nature, but are 
different, viz. palpitation, pulsation, and respiration. 

2 Now, palpitation is a compression of heat in the heart, 
owing to cooling in other parts of the body produced 
by excretion or waste, such as we see in the disease 
called palpitation of the heart, as well as in other 
diseases, and in fear also. In fear the upper regions 
of the body are cold, and their heat is discharged 
and collected in the heart, where palpitation is caused^ 
and the heat being thus compressed into a small space, 
it sometimes happens that animals are suffocated and 

3 die from fear and its morbid conditions. The pheno- 
menon of pulsation, however, that occurs in the hearty 
and which, as we see, is a constant process, is similar 
to the throbbing in an abscess. In the latter the move- 
ment is painful owing to abnormal change in the blood. 
This process continues to a point where the blood is 

4 concocted and converted into pus. The condition is 
analogous to boiling. For boiling takes place when 
water is evaporated by heat, and it bubbles up owing to 



its increase in volume. The development of abscesses 
is arrested when the pus is not evaporated and the liquid 
becomes very thick; the process in boiling is arrested 480 « 
when the confining vessel is overflowed. The supply of 5 
moisture derived from food and its expansion through 
heat produces pulsation in the heart, — the expansion 
extending to the heart's outer covering. And this is a 
constant process, for the flow of fluid to the heart, out of 
which the blood is generated, is constant. It is in the 
heart that blood is first formed. One can observe this 6 
plainly in the growth of an embryo.^ For before the 
veins are distinguishable the heart is seen to contain 
blood. Pulsation, for this reason, is more marked in 
youth than in old age. For the process of evaporation 
is stronger in youth. The blood vessels all pulsate, and 7 
they do so simultaneously, for they are all connected 
with the heart and originate in it. The heart, however, 
is in constant motion. So, too, the blood vessels are in 
constant motion, and simultaneously with each other, as 
long as the heart moves. Palpitation, then, is a re- 
action in the heart due to the compression of heat by 
the cooling of other parts of the body ; pulsation is the 
evaporation of the moist element as it becomes heated. 

^Cf. note 1, p. 276. 


Bespiration is due to the increase of the heated element, in 
which the nutritive principle is lodged. As all other bodily 
elements need maintenance, so does this element of vital 
heat, and even in a greater degree than the others, for it is 
the source of maintenance for the other elements. When 
it is increased, it necessarily expands the organ in which it 
2 is found. One must conceive the structure of this organ to 
resemble a brazier's bellows. For neither lungs nor heart 
differ very much from a form such as is illustrated by a 
bellows. Both are double.^ The nutritive principle must 
be situated in the centre of the vital power.^ The lungs 
then increase and expand, and, by expanding, the part 
in which they are lodged must also expand. We see this 
.3 when we respire. For the thorax is then expanded, 
because the inherent principle in this part is expanded. 
Owing to this expansion, as one sees in the bellows, 
cold air must be introduced from without and, by 
^3 its cooling effect, the excess of internal heat is lowered. 

' There wm a double as well as single form of bellows in nse in ancient 

' Ogle adopts a conjecture of Mr. Poste — ylnncriKrjs for ^wntdis, 



But just as the oigan was expanded owing to the increase 4 
of heat, so now it necessarily contracts when the heat is 
diminished, and by contracting, the air which was inhaled 
is again discharged — air that was cold when admitted, but 
warm when discharged owing to contact with the heat 
inherent in the organ, especially in the case of animals 
whose lungs are well-filled with blood. The air enters 
through a mass of pipps, canals as it were, with which the 
lungs are provided, and blood vessels extend alongside each 
of these pipes, so that the entire lung appears to be filled 
with blood. The admission of air is termed inspiration, 5 
and its discharge, expiration. The process of respiration 
is continuous, so long as life and this organic motion 
continue. Life, therefore, is given in the processes of 
inspiration and expiration. The movement of the gills 
in fishes is produced in the same way. For by the 6 
expansion of the blood's heat in its course through the 
members, the gills are lifted and water passes through. 
When, on the other hand, the heat retreats to the heart 
through the channels and cooling is efiected, the gills are 
lowered and the water passes out. The expansion of the 
heart's heat is constant and its re-admission when cooled 
is constant. And so in animals provided with lungs, life 
and death are ultimately conditioned by respiration, and 
in fishes by the admission of water. 

This, then, is a statement of our views of life and death 7 
and of almost all the questions germane to them. It is 
the province not only of the physician, but also of the 
natural philosopher, up to a certain point,^ to discuss 
questions of health and disease. We must not, however, 

^ Reading m^xP* tov for m^xP* red. 

330 Aristotle's psychology d« mbfir. 

forget how these two classes of men differ and how they 
regard a subject from different points of view, although 
experience shows that both professions are, to a certain 
extent at least, conterminous. For the better educated 
and more painstaking physicians are conversant with the 
laws of nature and deem it correct to derive their principles 
of practice from this source, while the best trained 
philosophers^ of nature almost always conclude with a 
discussion of the principles of medicine. 

^Cf. De 9en9u, 436a 19 £f. 


*»* The following works havo been found valuable in the preparation of the 

E resent volume. Further titles are referred to in the notes. Cmly such works are 
icluded as have immediate reference to the Psychology. For a more varied and 
complete bibliography see M. Schwab, BiUioffntphie ^AruioU (Paris, Librwie H. 
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Aristotle. De anima. Recen. A. Torstrik. Berolini, 1862. 

— De anima. Becog. et comment, illoat. Trendelenburg. Ed. altera. 

Berolini, 1877. 

— De anima. Becog. W. Biehl. Lipsiae, 1884. 

— De anima lib. B secundum recensionem vaticanam. Ed. H. Rabe. 

Berolini, 1891. 

— Parva naturalia. Becog. W. Biehl. Lipsiae, 1898. 

— Opera omnia, ex recensione Bekkeri. 5 voL Berolini, 1831-1870. 

— Opera omnia, ex recensione Bekkeri. 11 vol. Oxonii, 1837. 

— Opera omnia graece et latine. 5 vol. Parisiis, Didot, 1848-1869. 

Barth^lemy-St.-Hilaire, Psychologie (Traits de Time), trad, par 
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— Psychologie (Opuscules), trad, par Barth41emy-St.-Hilaire. Paris, 


Biiumker, C. Des Aristoteles Lehre von den liussern und innem 
Sinnesvermogen. Leipzig, 1877, pp. 91. 

Beare, J. L Aristotle's Parva Naturalia. Hermathena, vol. ix. (1894), 
pp. 1-29. 

— Notes on Aristotle's Parva Naturalia. Hermathena, voL x. (1899)» 

pp. 455-473. 

Beck, H. Anstoteles de sensuum actione. Berolini, 1860, pp. 55. 

Bender, W. Schrif t tlber die Seele. tubers, von Bender. Stuttgart, 

— Die kleinen naturwissenschaftlichen Schriften (Parva Naturalia). 

tubers, von Bender. Stuttgart, 1873. 

Biehl, W. t)ber die aristotelische Definition der Seele. Leipzig, 
1863. Verhandlunsen der 21sten. Versammlung deutacher 
Philologen und Schmmanner zu Augsburg, pp. 94-102, 

— Ober den Begriff podt bei Aristoteles. Linz, 1864, pp. 20. 

Biese, R. Die Erkenntnisslehre des Aristoteles und Kant's in 
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Bobba, R. La dottrina dell' intelletto in Aristotile. Torino, 1896» 
pp. 479. 



Bonitz, H. Ariatotelische Stadien. Wien, 1863-67. 

— t^r das ente Buch der aristoteL Schrift tlber die Seele. 

Monateber. der KdnigL Preats. Akad. d. Wiss., 1873, pp. 481 tL 

Brentano, F. Von der mannifffachen Bedeutung des Seienden nach 
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— Die Paychologie des Ariatoteles, insbesondere seine Lehre vom woOt 

voirrriKds, Mainz, 1867, pp. 252. 

— 0£fener Brief an Herm Professor Dr. Ednard Zeller. Leipzig, 

1883, pp. 36. 

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— Aristoteles' Nos-Lehre. Dillingen, 1882, pp. 73. 

Chaignet, A. K Essai snr la psychologie d'Aristote. Paris, 1883. 

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Eberhard, E. Die aristotelische Definition der Seele and ihr Worth 
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Freudenthal, J. tJTber den Begrifif des Wortes ^amala bei 
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sophie und die Bedeutung der Phantasie in derselben. Mttnchen, 
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Granger, F. Aristotle's Theory of Reason. Classical Review, VoL 
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— Aristotle's Theory of Reason. Mind, VoL zviii. (1893), pp. 307-318. 

Grote, G. Aristotle. London, 1872, 2 vols. 

Guthling, K. E. Die Lehre Aristoteles von den Seelentheilen. 
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Hammond, W. A. Aristotle's Doctrine of ^arrcurla. Proceedings of 
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— Kleine Abhandlnngen iiber die Seele. tubers, von Krenz. 

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Philibert, H. Du principe de la vie suivant Aristote. Paris, 1865. 

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Poppelreuter, H. Zur Psychologic des Aristoteles, Theophrast, 
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Bitter, B. Die Grundprincipien der aristotelischen Seelenlehre. 
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— Aristotle and the Earlier Peripatetics, translated by Costelloe and 
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AbBtraotion, 125. 

ActaaUty, 43, 63 f. 

Affections, nature of, 29. 

After-image, 236. 

Air, as medium,. 76 ff. 

Alcmaeon, 16. 

Anaxagoras, on respiration, 288 ; 
on soul, 12-17. 

Anger, definition of, 8. 

Animals, classification of, 171 
distinguished from plants, 272 
longevity of, 263, 266, 304 
ovoviviparous, 307. 

Animate, 10. 

Animism, 49. 

Appetite, 133. 

Association of ideas, 205. 

Atomic theory, vid, under Demo- 

Birth, 324. 

Blood, oiroulation, 227 ; effect on 
dreams, 242; movements in, 

Body, dissection o^ 303 ; divisions 
of, 273 ; elements in, 60 ; poten- 
tiality, 46 ; relation to soul, 40- 

Brain, oigan of cooling, 80, 228 ; 
size in man, 176. 

•. . . " 

Categories, 4. 

Cause, meanings of, 58, 220, 248. 

Chance, 250. 

Cognition, 35. 

Colour, explanation of, 71, 158, 
160; number of, 168; primary 
colours, 87. 

Common sense, in consciousness, 
99 ; in judgment, 103 ; in sense- 
perception, 97; in unification, 

Common sensibles, 97 ff., 232. 
Conception, 106. 

Conduct, reason and desire in. 

Consciousness, in sleep, 245-253. 
Continuity, 120, 181. 
Critias, 16. 

Death, 261. 

Deduction, 6. 

Definition, 6, 8, 23, 48. 

Deliberation, 136. 

Democritus, atomic theory, 32; 
dreams, 252 ; theory of soul, 11, 
15, 21, 30, 32, 37 ; primary and 
secondary qualities, 101 ; respira- 
tion, 288-294; touch, 169; 
vision, 153. 

Desire, 54, 123, 133, 137. 

Diaphanous, 71, 73, 158 f., 171. 

Dioffenes of Apollonia, 15, 288, 

Disjunction, 119. 
DivisibiUty, 39 ffl, 120. 




Dreams, atribiliooB, 254 ; memory 
of, 246 ; observation of, 245 ; 
origin of, 231, 251 ; prophetic, 

Echo, 76. 

Emotions, 8. 

Empedocles, on evolation, 315 
srowth, 59 ; harmony, 27 
knowledge, 35; Ught, 72 
movement of blood, 300 ; respira 
tion, 299 f. ; sonl, 13, 27, 34 
taste, 164 ; vision, 151 f. 

Enteleohy, 42, 44. 

Environment, 317. 

Epiglottis, 310. 

Error, 119. 

Eye, 153.155. 

Faculties, vid, under Soul ; classi- 
fication of, 54, 57, 58. 

Feelings, physically expressed 
ideas, 6-8. 

Flavour, vid, under Taste. 
Democritus on, 170; haptic 
quality, 55 ; primary flavours, 
87 ; theories of, 164-167, 

Form, 42, 53, 220. 

Frogs, artificial, 244. 

Good and bad, 124. 

Hard flesh, 41. 

Harmony, relation to soul, 26 ff., 
102 ; Xenocrates on, 30. 

Hearing, importance of, 144, 148, 
149 ; nature of, 76 ff. ; organ of, 


Heart, centre of life, 275 ; connec- 
tion with lungs, 318 ; first organ 
to develop, 277 ; orsan of 
nutrition, 302; organ of sensa- 
tion, 279 ; palpitation, 326 ; 
structure of, 229. 

Heat, animal, 280, 303, 322 ; con- 
trolled by respiration, 295. 

Heraclitus, 15. 

Hippo, 15. 

Ideas, association of, 205. 

ninsion, example of, 240 ; in 
dreams, 239. 

Imagination, control of, 106; de- 
finition of, 107, 110 ; diatin. 
ffuished from memory, 201 ; in 
dreams, 234, 242, 245 ; organ of 
240; productive and reprodne- 
tive, 56; relation to thoo^t, 
109, 123, 127, 198 ; reUtion to 
desire, 135 ; residual sensatioii, 

Immortality, 61, 58. 

Insects, live after diviaion, 274; 
respiration of, 306. 

Ionian physiologers, 17. 

Judgment, function of oommon 
sense, 103 ; function of thonefat ; 
128 ; inhibition of in sleep, 243. 

Knowledge, actual and potential, 
122 ; kinds of, 1, 48 ; two 
powers of knowing, 231. 

Leucippus, 11. 

life, centralisation of, 276 ; con- 
nection with vital heat, 280, 
322 ; destruction of, 258, 281, 
324 ; duration of, 256, 262, 267, 
304 ; in insects, 268 ; meanings 
of, 49 ; relation to respiration, 
293, 329; seat of, 271; onity 
of, 275. 

li^ht, cause of vision, 152, 185 ; 
diaphanous, 71 ; motion, 184 ; 
nature of, 157. 

Locomotion, 129. 

Longevity, 256, 265. 

Lungs, coexist with gilla, 308 ; 
function of, 80, 308 ; organ of 
refrigeration, 318 ; organ of 
respiration, 306 ; spongy, 307 ; 
structure of, 328. 

Magnitude, relation to sensation, 
162, 181. 

Man, most intelligent iinim^l^ g2. 

Matter, 42. 

Medicine, connection with philo- 
sophy of nature, 147, 330. 



Medium, condition of sense-per- 
ception, 73 ff., 183 ; for percep- 
tion at distance, 140 ; of sound, 
75 ; of touch, 89 S, 

Memory, definition of, 195: im- 
print of seal-ring, 199 ; in youth 
and old age, 199 ; processes of, 
209 ; object of, 196 ; relation to 
imagination, HI, 201 ; relation 
to reason, ^ ; relation to time, 
197, 210 ; seat of, 202 ; why 
strengthened by exercise, 202. 

Method, kinds of, 3. 
Monad, soul a, 30. 

Motion, Democritus on, 21 ; de- 
fined, 19, 37, 223 ; in conduct, 
133, 137 ; in sleep, 242 ; Platonic 
theory of, 19 ; relation to light, 
72; relation to sensation, 65, 
238 ; relation to soul, 18, 23, 28, 

Myths, Pythagorean, 24. 

Nature, purpose in, 59, 221. 

Nominalism, 4. 

Number-theory, 32. 

Nutrition, faculty of, 57, 62 f., 
138 ; organ of, 273 ; relation to 
smell, 174 ; seat of, 271, 276 ; 
shared by plants, 50 ; sweet in, 

Old age, 270, 324. 

Opinion, not possessed by lower 
animals, 136 ; relation to imagi- 
nation, 111. 

Orphic verses, 37. 

Palpitation, 326 f. 

Parva Naturalia, 145. 

Perception, limits of, 193 ; per- 
ceptibility and magnitude, 182 ; 
umty in, 192. 

Phantasy, vid. under Imagination. 

Philaegides, 254. 

Philosophy of nature, relation of 
to meidicine, 147, 330. 

Plants, differentiated fromanimals, 
272 ; duration of life in, 267 ; 

heat in, 284, 302; soul in, 41, 
50 ; without sensation, 94. 

Plato, 'circular push,' 296; Dis- 
courses en Philosophy f 13 ; facul- 
ties of soul, 51 ; on motion, 14 ; 
nature of the soul, 13, 21, 33 ; 
THmaeus, 51, 151; on vision, 

Pleasure and pain, 61, 122. 

Potentiality, meaning of, 4, 44, 
64-68, 87; relation to know- 
ledge, 66, 100. 

Pre- Aristotelian psychology, 1 1 ff. , 
26 ff. 

Predication, 121. 

Principle, meaning of, 2. 

Proof, demonstration, 23. 

Psychology, pre- Aristotelian, 10 ff. 

Pulsation, 326. 

Pythagoreans, myths, 24; nature 
of soul, 11, 17, 24, 26, 53; 
respiration, 298. 

Qualities, primary and secondary, 

Realism, 4. 

Reason, active, 47, 112-118; 
Anaxagoras on, 12 ; divine nature 
of, 29 ; epitactic, 130, 132 ; in- 
destructible, 29; practical, 124, 
125, 135; relation to imagina- 
tion, 110 ; separability from 
body, 24; thinks abstractions, 
125 ; thinks external world, 181 ; 
time necessary to, 197; unify- 
ing principle, 120. 

Recollection, definition of, 195; 
deliberation in, 2U; different 
from memory, 204; how pro- 
duced, 206; in youth and old 
ase, 212 ; movement from within, 
iS; not shared by lower ani- 
mals, 211. 

Reflex-movement, 275. 

Refrigeration, organs of, 80; pur- 
pose of, 284. 

Respiration, in aquatic animals, 
289, 291, 311 ; functions of, 297 ; 
in insects, 305; organ of, 301 ; 



in old age, 320; Plato's theory 
of, 296; purpose of, 286; in 
whales, 311. 

Sapid, defined, 85, 86. 

Sensation, activity of, 237; com- 
mon sense, 70, 97, 99; co- 
ordination in, 189; definition 
of, 93, 112; duration of, 190; 
in dreams, 233; fusion, 187; 
medium, 182; mean, 92; move- 
ment from without, 29 ; organs 
of, 96; necessary to ammal 
life, 138; persistence of, 239; 
purpose of, 147 ; qualitative 
change, 236; relation to heart, 
277; relation to thought, 106; 
seat of, 279; simultaneity in, 
186; in sleep, 241, 249. Vid, 
under the particular senses. 

Sense-object, 69, 102. 

Sense-perception, 64 ff., 101. 

Sense-quality, 69, 181. 

Senses, correlated with physical 
elements, 160; five, 95 ff. ; higher 
and lower, 140, 148. 

Sensibility, relation to magnitude, 
180, 193. 

Sensibles, common, 97 ff., 232. 

Sight, vid, under Vision; impor- 
tance of, for higher life, 144, 

Sign, definition of, 248, 252. 

Simultaneity of sensations, 190 ff. 

Sleep, cause of, 218, i^, 226 f., 
230; consciousness in, 215, 244; 
function of, 216; heaviness in, 
225; mantic character of, 247; 
movements in, 223; necessary 
to animal life, 216, 221; organ 
of, 215, 222; sensation in, Sill ; 
tractoteon, 213 ff. 

Smell, air affected by, 94; classifi- 
cation of smells, 83, 173; ex- 
halation, 155; inaccurate in 
man, 82, 164; in air and water, 
171, 177; medium required by, 
74, 84; middle position of, 177; 
nature of, 82 n. ; relation to 
flavour, 83, 164, 174 ; relation to 
respiration, 175; 'sapid dry,' 
172; theories of, 173 ff. 

Soul, Alcmaeon on, 16; Anaxa- 
goras on, 16; atomic theory of, 
11; body related to, 6, 7, 9, 
29, 40, 53, 58, 146; centraliaa- 
tion of, 274; Critias on, 16; 
definition of, 45-52, 55, 56; 
Democritus on, 11, 15; Dio- 
genes> on, 15; elements related 
to, 33 f., 37, 38; Empedocles 
on, 13 ; etymology of word, 17 : 
faculties of, 40, 51, 54, 57, 133 ; 
final cause, 59 ; fire, 60 ; har- 
mony, 26 f. ; Heraclitns on, 15 ; 
Hippo on, 16; immortality of, 
6, 7, 31, 47, 51 ; knowledge, 41 ; 
Leucippus on, 11 ; life, S9, 49 ; 
motion, 10, 19 ff., 30, 37; num- 
ber-theory, 30, 32; nutrition, 
50, 61 ff., 271 ; Plato on, 13, 
51 ; pre* Aristotelian theories of, 
10 ff. , 1 3, 33 ; principle in plants, 
41; reality, 126; separability 
of, 6f., 31, 47, 51; substance, 
42; Thales on, 15; unity of, 40, 
51 ; Xenocrates on, 30. 

Sound, of insects, 305 ; nature of. 

75 ff. 

Stimuli, excessive, 93, 102. 

Substance, meanings of, 42, 44» 

Taste, accurate in man, 82 ; nature 
of, 85 f.; primary flavours, 87; 
touch and, 139, 164. 

Temperature, regulation of, 80. 

Thales, soul kinetic, 15 ; pan- 
psychism, 38. 

Theophrastus, on sound, 75. 

Theories of soul, history of, 11 ff. 

Thought, vid. under Reason, defi- 
nition of, 106 ; dependent on 
will, 67 ; discursive, 29 : identi- 
cal with object, 125; inde- 
pendence of body, 6; image 
necessary to, 6, 197; somatic, 

Time, 191. 

Touch, accuracy of, in man, 82; 
analogy to hearing. 79; direct 
action of, 142; function of, 
69; fundamental character of, 
50, 52, 54-56, 139, 142, 143; 



medium of, 85, 89-91; n&tnre 
of, 88 ff., 169; organ of, 89; 
tMte and, 55. 

Univenals, nature of , 4 ; in the 
mind, 67. 

Vision, vid. under Sight ; con- 
nected with fire, iS; Demo- 
critus on, 153 ; effect on object, 
237 ; Empedocles on, 152 ; eye 
as organ of, 155 ; medium of, 
141 ; nature of, 71 ; Plato on, 
151; theories of, 150 ff. 

Voice, significant sound, 79-81. 

Waking, definition of, 214. 

Whales, spout-organ in, 312. 

Will, kinetic aspect of reason, 

Windpipe, 309. 

Words, symbols, 149. 

Xenocrates, 30-33. 

Youth, and old age, 270. 





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